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111.
A graph is called s-regular if its automorphism group acts regularly on the set of its s-arcs. In this paper, the s-regular cyclic or elementary abelian coverings of the Petersen graph for each s ⩾ 1 are classified when the fibre-preserving automorphism groups act arc-transitively. As an application of these results, all s-regular cubic graphs of order 10p or 10p 2 are also classified for each s ⩾ 1 and each prime p, of which the proof depends on the classification of finite simple groups.  相似文献   
112.
This paper presents explicit formulas for shape sensitivity analysis of thin shell structures. The curvature distribution is the design to be determined. The thin-shell theory employed is the general Koiter model in the Cartesian coordinates. For the shape sensitivity formulation, both the direct differentiation method and the material derivative concept have been used. The two formulations are shown to be equivalent. A computer program based on these formulations has been developed and applied to examples. The shape sensitivity results obtained have been compared to those obtained by finite differencing.  相似文献   
113.
This article concerns the hydrosilylation polyaddition of 1,4‐bis(dimethylsilyl)benzene ( 1 ) with 4,4′‐diethynylbiphenyl, 2,7‐diethynylfluorene ( 2b ), and 2,6‐diethynylnaphthalene with RhI(PPh3)3 catalyst. Trans‐rich polymers with weight‐average molecular weights (Mw's) ranging from 19,000 to 25,000 were obtained by polyaddition in o‐Cl2C6H4 at 150–180 °C, whereas cis‐rich polymers with Mw's from 4300 to 34,000 were obtained in toluene at 0 °C–r.t. These polymers emitted blue light in 4–81% quantum yields. The cis polymers isomerized into trans polymers upon UV irradiation, whereas the trans polymers did not. The device having a layer of polymer trans‐ 3b obtained from 1 and 2b demonstrated electroluminescence without any dopant. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2774–2783, 2004  相似文献   
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The main aim of this paper is to give some upper and lower bounds for the isoperimetric numbers of graph coverings or graph bundles, with exact values in some special cases. In addition, we show that the isoperimetric number of any covering graph is not greater than that of the base graph. Mohar's theorem for the isoperimetric number of the cartesian product of a graph and a complete graph can be extended to a more general case: The isoperimetric numberi(G × K 2n) of the cartesian product of any graphG and a complete graphK 2n on even vertices is the minimum of the isoperimetric numberi(G) andn, and it is also a sharp lower bound of the isoperimetric numbers of all graph bundles over the graphG with fiberK 2n. Furthermore, ifn 2i(G) then the isoperimetric number of any graph bundle overG with fibreK n is equal to the isoperimetric numberi(G) ofG. Partially supported by The Ministry of Education, Korea.  相似文献   
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