Papers by Keyword: Contour Line

Abstract: The cause of heavy metal contamination in urban topsoil is discussed. Use factor analysis method on a single factor pollution index matrix,to screen three common factors whose accumulative contribution rate accounts for 95%, and then analyze coefficients of the rotating component matrix, and extract several heavy metal elements significantly associated with common factors for a comprehensively analysis of the cause of contamination.The results are as follows: the first common factor is significantly correlated with heavy elements Hg, Cu and Cd, whose main cause is industrial pollution; the second common factor is significantly correlated with heavy elements As, Pb and Zn, whose main causes are traffic pollution and industrial pollution; the third common factor is significantly correlated with elements Cr, Ni and Zn, whose main causes are domestic pollution and industrial pollution.

Abstract: Groundwater pollutions visualization can be come true by interpolation with monitoring data, which is very helpful to know the situation of regional pollution. In this paper, the spatial database is constructed by GIS software, it is used to manage the monitoring data dynamically, adopting the component GIS, the monitoring data can be easily loaded into the developing environment, by the contour and contour line method, the contour line of groundwater pollutants can be acquired, which is very important to visualize the regional pollution situation.

Abstract: A numerical simulation method for the wind field over complex terrain is developed in this paper. The complex terrain is represented by a surface, which is established by the surface spline method basing on the contour line of the map. Then it is divided into panels containing vortex ring singularities. The singularity distribution is solved by combining with the potential flow theory and the boundary condition of terrain surface. Finally, the wind field is simulated by linear superposition of the uniform stream and the induced velocity of vortex rings. A numerical example is studied, and the result indicates that the method proposed in this paper could describe the terrain much more accurately and provide a reasonable result of wind field distribution, but has a simple and efficient procedure, which is suitable for the engineering use in flight dynamics.

Abstract: Contour line map and digital terrain model are widely used in practical work. With the rapid development of computer technology, computer graphics and geographic information system, they become more and more practical and their roles have become more prominent. Contour line has incomparable advantage of expressing both qualitative and quantitative information especially in the terrain analysis. Many algorithms of contour line map are automatically generated based on the digital terrain model.

Abstract: At present there are diverse algorithms in generating 3d terrain,to further improve the efficiency of the algorithms and fidelity of the 3d terrain,a new method generating 3d terrain by digital geographical topographic map was put forward.First extract the contour lines from the map and thin the contour lines by a improved thinning algorithm based on mathematical morphology[1].In the process of interpolation,the digital elevation map of terrain can be got by interpolation in vertical and horizontal directions,and the method of intra-interpolation and extra-interpolation according to the distribution of contour lines was also used.The terrain got by this method can reflect the details and the tendency of the terrain.The digital geographical topographic map on the network can reflect the change of the terrain timely because of its high updating speed.This method has great practical value