Conventionally, the design of linear-phase 2-D FIR digital filters is concentrated on the class of quadrantally symmetric filters, such as circular filters, fan-type filters etc [l]. A 2-D sequence, which is symmetric in both directions, is required to realize such quadrantally symmetric filters. In this paper, we will start from the discussion of the symmetric properties of 2-D sequences to di...

This paper presents a new approach for intuitive and effective design of periodic symmetric tiles. We observe that planar graphs can effectively represent symmetric tiles and graph drawing provides an intuitive paradigm for designing symmetric tiles. Moreover, based on our theoretical work to represent hexagonal symmetry by rectangular symmetry, we are able to present all symmetric tiles as gra...

We present a family of mixed methods for linear elasticity, that yield exactly symmetric, but only weakly conforming, stress approximations. The method is presented in both two and three dimensions (on triangular and tetrahedral meshes). The method is efficiently implementable by hybridization. The degrees of freedom of the Lagrange multipliers, which approximate the displacements at the faces,...

Let D be a symmetric design admitting a null polarity such that either all singular lines, or all nonsingular lines, have size (v − λ)/(k − λ); assume that this number is greater than λ in the case of singular lines. Then D is either a projective space or an orthogonal symmetric design. © 2003 Elsevier Ltd. All rights reserved. The Dembowski–Wagner Theorem [3] characterizes projective spaces as...

Workpiece localization has many applications in manufacturing automation. Symmetric localization plays an important role in it, since many commonly used features in engineering design are symmetric. In this paper, we discuss some new problems in symmetric localization. We find that multiple solutions exist even for localizing a cube, while it was known that a unique solution should be found. Th...

This paper presents a new approach for intuitive and effective design of periodic symmetric tiles. We observe that planar graphs can effectively represent symmetric tiles and graph drawing provides an intuitive paradigm for designing symmetric tiles. Moreover, based on our theoretical work to represent hexagonal symmetry by rectangular symmetry, we are able to present all symmetric tiles as gra...

It is traditional to call a quasi-symmetric design with certain parameters an SDP design if the symmetric difference of two different blocks is either a block or a block complement. In this note, we delete the requirements on the parameters and demand just that the symmetric difference of two blocks be a block, a block complement, or either the empty set or the whole point set. We obtain the pa...

A graph is said to be symmetric if its automorphism group is transitive on its arcs. A complete classification is given of pentavalent symmetric graphs of order 24p for each prime p. It is shown that a connected pentavalent symmetric graph of order 24p exists if and only if p=2, 3, 5, 11 or 17, and up to isomorphism, there are only eleven such graphs.

A graph is called symmetric if its full automorphism group acts transitively on the set of arcs. The Cayley graph $Gamma=Cay(G,S)$ on group $G$ is said to be normal symmetric if $N_A(R(G))=R(G)rtimes Aut(G,S)$ acts transitively on the set of arcs of $Gamma$. In this paper, we classify all connected tetravalent normal symmetric Cayley graphs of order $p^2q$ where $p>q$ are prime numbers.

In this paper we study the automorphism group of a possible symmetric (81, 16, 3) design.