Since 1950, 700 plots were established in the alpine and canyon region of western Sichuan. The distribution charac-teristics and the relationships between forest succession and environmental gradients were studied. Th...Since 1950, 700 plots were established in the alpine and canyon region of western Sichuan. The distribution charac-teristics and the relationships between forest succession and environmental gradients were studied. The results showed that the main tree species were Picea and Abies in this region, and there were more than 90 forest types. Abies forests mainly dis-tributed in the middle and upper reaches of rivers and their branches, and Picea forests mainly distributed in wide valleys and on half-shaded and half-sunny slopes. The natural regeneration was poor under primitive spruce and fir forest canopy, but was good in the spruce and fire forest gap. The relationship between forest succession and vertical gradient was closely related to the relationship between forest succession procession and plant synusia under primary forests. Human activities could promote and postpone succession process. The results of expanding regeneration were often influenced by topography, vegetation and wind direction.展开更多
Let G be a simple graph and f be a proper total kcoloring of G. The color set of each vertex v of G is the set of colors appearing on v and the edges incident to v. The coloring f is said to be an adjacent vertex-dist...Let G be a simple graph and f be a proper total kcoloring of G. The color set of each vertex v of G is the set of colors appearing on v and the edges incident to v. The coloring f is said to be an adjacent vertex-distinguishing total coloring if the color sets of any two adjacent vertices are distinct. The minimum k for which such a coloring of G exists is called the adjacent vertex-distinguishing total chromatic number of G. The join graph of two vertex-disjoint graphs is the graph union of these two graphs together with all the edges that connect the vertices of one graph with the vertices of the other. The adjacent vertex-distinguishing total chromatic numbers of the join graphs of an empty graph of order s and a complete graph of order t are determined.展开更多
Segmenting the touching objects in an image has been remaining as a hot subject due to the problematic complexities, and a vast number of algorithms designed to tackle this issue have come into being since a decade ag...Segmenting the touching objects in an image has been remaining as a hot subject due to the problematic complexities, and a vast number of algorithms designed to tackle this issue have come into being since a decade ago. In this paper, a new granule segmentation algorithm is developed using saddle point as the cutting point. The image is binarized and then sequentially eroded to form a gray-scale topographic counterpart, followed by using Hessian matrix computation to search for the saddle point. The segmentation is performed by cutting through the saddle point and along the maximal gradient path on the topographic surface. The results of the algorithm test on the given real images indicate certain superiorities in both the segmenting robustness and execution time to the referenced methods.展开更多
基金This article was supported by State Tenth Five-Year Plan Project (2001BA510B0105) and the Project for Pioneering New Knowledge from Chinese Academy of Sciences (KZCX2-SW-319).
文摘Since 1950, 700 plots were established in the alpine and canyon region of western Sichuan. The distribution charac-teristics and the relationships between forest succession and environmental gradients were studied. The results showed that the main tree species were Picea and Abies in this region, and there were more than 90 forest types. Abies forests mainly dis-tributed in the middle and upper reaches of rivers and their branches, and Picea forests mainly distributed in wide valleys and on half-shaded and half-sunny slopes. The natural regeneration was poor under primitive spruce and fir forest canopy, but was good in the spruce and fire forest gap. The relationship between forest succession and vertical gradient was closely related to the relationship between forest succession procession and plant synusia under primary forests. Human activities could promote and postpone succession process. The results of expanding regeneration were often influenced by topography, vegetation and wind direction.
基金The Fundamental Research Funds for the Central Universities of China(No.3207013904)
文摘Let G be a simple graph and f be a proper total kcoloring of G. The color set of each vertex v of G is the set of colors appearing on v and the edges incident to v. The coloring f is said to be an adjacent vertex-distinguishing total coloring if the color sets of any two adjacent vertices are distinct. The minimum k for which such a coloring of G exists is called the adjacent vertex-distinguishing total chromatic number of G. The join graph of two vertex-disjoint graphs is the graph union of these two graphs together with all the edges that connect the vertices of one graph with the vertices of the other. The adjacent vertex-distinguishing total chromatic numbers of the join graphs of an empty graph of order s and a complete graph of order t are determined.
基金Ningbo Natural Science Foundation (No.2006A610016)Foundation of the Ministry of Education Ministry for Returned Overseas Students & Scholars (SRF for ROCS, SEM. No.2006699).
文摘Segmenting the touching objects in an image has been remaining as a hot subject due to the problematic complexities, and a vast number of algorithms designed to tackle this issue have come into being since a decade ago. In this paper, a new granule segmentation algorithm is developed using saddle point as the cutting point. The image is binarized and then sequentially eroded to form a gray-scale topographic counterpart, followed by using Hessian matrix computation to search for the saddle point. The segmentation is performed by cutting through the saddle point and along the maximal gradient path on the topographic surface. The results of the algorithm test on the given real images indicate certain superiorities in both the segmenting robustness and execution time to the referenced methods.
