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任意拉格朗日—欧拉描述法研究进展 总被引:45,自引:1,他引:45
任意拉格朗日描述综合了纯拉格朗日和纯欧拉描述的优点,克服了各目的缺点,成为非线性连续介质力学中大变形分析的非常有效的方法。本文论述了ALE法的研究进展及其在流动流体动力学、流体-结构相互作用、加工成型、碰撞、接触等大变形问题中的应用。 相似文献
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For a given -partition of the vertices of a (di)graph , we study properties of the spanning bipartite subdigraph of induced by those arcs/edges that have one end in each . We determine, for all pairs of nonnegative integers , the complexity of deciding whether has a 2-partition such that each vertex in (for ) has at least (out-)neighbours in . We prove that it is -complete to decide whether a digraph has a 2-partition such that each vertex in has an out-neighbour in and each vertex in has an in-neighbour in . The problem becomes polynomially solvable if we require to be strongly connected. We give a characterisation of the structure of -complete instances in terms of their strong component digraph. When we want higher in-degree or out-degree to/from the other set, the problem becomes -complete even for strong digraphs. A further result is that it is -complete to decide whether a given digraph has a -partition such that is strongly connected. This holds even if we require the input to be a highly connected eulerian digraph. 相似文献
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A new infinite family of simple indecomposable one‐factorizations of the complete multigraphs is constructed by using quadrics of finite projective spaces. © 2002 Wiley Periodicals, Inc. J Combin Designs 10: 139–143, 2002; DOI 10.1002/jcd.997 相似文献
36.
LetλKm,n be a bipartite multigraph with two partite sets having m and n vertices, respectively. A Pv-factorization of λKm,n is a set of edge-disjoint Pv-factors of λKm,n which partition the set of edges of λKm,n. When v is an even number, Ushio, Wang and the second author of the paper gave a necessary and sufficient condition for the existence of a Pv-factorization of λKm,n. When v is an odd number, we proposed a conjecture. However, up to now we only know that the conjecture is true for v= 3. In this paper we will show that the conjecture is true when v= 4k- 1. That is, we shall prove that a necessary and sufficient condition for the existence of a P4k-1-factorization of λKm,n is (1) (2κ - 1)m ≤ 2kn, (2) (2k - 1)n ≤ 2km, (3) m + n ≡0 (mod 4κ - 1), (4) λ(4κ - 1)mn/[2(2κ - 1)(m + n)] is an integer. 相似文献
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Benjamin R. Smith 《组合设计杂志》2010,18(6):401-414
In this article, we introduce a new technique for obtaining cycle decompositions of complete equipartite graphs from cycle decompositions of related multigraphs. We use this technique to prove that if n, m and λ are positive integers with n ≥ 3, λ≥ 3 and n and λ both odd, then the complete equipartite graph having n parts of size m admits a decomposition into cycles of length λ2 whenever nm ≥ λ2 and λ divides m. As a corollary, we obtain necessary and sufficient conditions for the decomposition of any complete equipartite graph into cycles of length p2, where p is prime. © 2010 Wiley Periodicals, Inc. J Combin Designs 18:401‐414, 2010 相似文献
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In this paper, as a generalization of the binomial random graph model, we define the model of multigraphs as follows: let
G(n; {p
k
}) be the probability space of all the labelled loopless multigraphs with vertex set V = {υ
1, υ
2, …, υ
n
}, in which the distribution of tvi ,vj t_{v_i ,v_j } , the number of the edges between any two vertices υ
i
and υ
j
is
P{ tvi ,vj = k} = pk ,k = 0,1,2,...P\{ t_{v_i ,v_j } = k\} = p_k ,k = 0,1,2,... 相似文献
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We consider multigraphs G for which equality holds in Vizing's classical edge colouring bound χ′(G)≤Δ + µ, where Δ denotes the maximum degree and µ denotes the maximum edge multiplicity of G. We show that if µ is bounded below by a logarithmic function of Δ, then G attains Vizing's bound if and only if there exists an odd subset S?V(G) with |S|≥3, such that |E[S]|>((|S| ? 1)/2)(Δ + µ ? 1). The famous Goldberg–Seymour conjecture states that this should hold for all µ≥2. We also prove a similar result concerning the edge colouring bound χ′(G)≤Δ + ?µ/?g/2??, due to Steffen (here g denotes the girth of the underlying graph). Finally we give a general approximation towards the Goldberg‐Seymour conjecture in terms of Δ and µ. © 2011 Wiley Periodicals, Inc. J Graph Theory 69:160‐168, 2012 相似文献
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A digraph D is supereulerian if D has a spanning eulerian subdigraph. BangJensen and Thomass′e conjectured that if the arc-strong connectivity λ(D) of a digraph D is not less than the independence number α(D), then D is supereulerian. In this paper, we prove that if D is an extended cycle, an extended hamiltonian digraph, an arc-locally semicomplete digraph, an extended arc-locally semicomplete digraph, an extension of two kinds of eulerian digraph, a hypo-semicomplete digraph or an extended hypo-semicomplete digraph satisfyingλ(D) ≥α(D), then D is supereulerian. 相似文献
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