Forney conjectured the existence of a “normal realization” (NR) for the [24,12,8] Golay code in which the code appears as a tetrahedron, with 6 output channel bits at each of the 4 vertices and 2 state bits carried by each of the 6 edges. Although the conjecture was dashed by Vardy, we here give a quasi-cyclic NR exhibiting tetrahedral symmetry, confirming the common wisdom that Forney is never...

Received Revised We discuss a point-group-theory based method of searching for new regions of nuclear stability. We illustrate the related strategy with realistic calculations employing the tetrahedral and the octahedral point groups. In particular, several nuclei in the Rare Earth region appear as excellent candidates to study the new mechanism.

The case for liquid water having non-tetrahedral as well as tetrahedral coordination is put forward. Given the dependence of structure on the hydrogen bond definition, a recent conceptual breakthrough has been the topological hydrogen bond definition which overcomes the shortcomings of traditional cut-off-based hydrogen bond definitions. It identifies the hydrogen bonds in water's first coordin...

A pseudo-triangulation is a cell complex in the plane whose cells are pseudo-triangles, i.e., simple polygons with exactly three convex vertices (so-called corners). Being an interesting and flexible generalization of triangulations, pseudo-triangulations have found their place in computational geometry; see e.g. [8, 11, 7, 1] and references therein. Unlike triangulations, pseudo-triangulations...

An adaptive method that robustly produces high aspect ratio tetrahedra to a general 3D metric specification without introducing hybrid semi-structured regions is presented. The elemental operators and higher-level logic is described with their respective domaindecomposed parallelizations. An anisotropic tetrahedral grid adaptation scheme is demonstrated for 1000–1 stretching for a simple cube g...

A more automatic method for generation of tetrahedra and directional surface meshes are the two developments presented in this paper. Un-structured grids are generated for complex 3-D ge-ometries including multi-body domains. A combined octree-advancing front method is presented for the generation of the unstructured surface mesh as well as the tetrahedral volume mesh. The unique feature of thi...

A new modeling approach is presented to improve numerical simulations of groundwater flow and contaminant transport in fractured geological media. The approach couples geological and numerical models through an intermediate mesh generation phase. As a first step, a platform for 3D geological modeling is used to represent fractures as 2D surfaces with arbitrary shape and orientation in 3D space....

In this article, we describe a detailed method for automatically generating tetrahedral meshes from 3D images having multiple region labels. An adaptively sized tetrahedral mesh modeling approach is described that is capable of producing meshes conforming precisely to the voxelized regions in the image. Efficient tetrahedral mesh improvement is then performed minimizing an energy function conta...

In the last years, substantial progress has been achieved in the area of volume visualization on irregular grids, which is mainly based on tetrahedral meshes. No attempts have been made so far to compress tetrahedral meshes losslessly, although this is especially important for scientific applications since even moderately fine meshes consume several mega-bytes of storage. In this paper we close...