SUMMARYThis paper presents a generalized method which generates linear, triangular, quadrilateral and pentahedral elements for the finite element method. Depending on geometrical and material variations, the region to be discretized is manually divided into blocks such as lines, triangles, quadrilaterals, pentahedrons and hexahedrons in several appropriate co-ordinate systems. However, no connectivity information of the adjacent blocks is required by the user as input. The continuity of the generated nodal co-ordinates and element configurations at the block interface are automatically maintained to describe the geometry of structures, no matter how these five types of blocks are connected. Furthermore, a mesh grading algorithm which generates reliable mesh grade distributions in the interior of the triangular and quadrilateral blocks is established corresponding to the arbitrarily defined subdivision numbers for each edge line of blocks. This algorithm is extended to the mesh grading in the interior of the hexahedral and pentahedral blocks. Element numbers are also renumbered in this scheme, in addition to node numbers, in order to increase the computational efficiency of the global matrix assembly. Additional facilities, i.e. loading data generation, boundary condition data generation and so on, are also discussed. An illustrative and a practical example are given to demonstrate the capabilities of this scheme.
Detection of Spontaneous Combustion of Coal by the Ratio of Alkanes by Jo TASHIRO, Makoto KONO and Isao TAKAKUWA The CO/O2 def. ratio, CO content and alkene content are used for the indicators of spontaneous heating underground. Now, we discovered a new method of the ratio of alkanes. The reliability of the new method was proved by laboratory experiments and on the site tests. When coal temperature rise slightly, the ratio of alkanes increase sensitively. Therefore, the ratio may become an excellent indicator of spontaneous combustion of coal.
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