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设珮犠(狋):犚犖+ →犚犱是犖指标犱维广义Wiener过程,对任意紧集犈1,…,犈犿犚犖> ,该文研究了犿项代数和珮犠(犈1)…珮犠(犈犿)的Hausdorff维数,Packing维数和正的Lebesgue测度及内点的存在性. 其结果包含并推广了布朗单的结果. 相似文献
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YIN JIANXING 《高校应用数学学报(英文版)》1994,(4)
PACKINGPAIRSBYQUINTUPLES:THECASEOFZEROCONGRUENCEMOD4YINJIANXINGAbstract:LetD(v)denotethemaximumnumberofquintuplesofav-setofpo... 相似文献
4.
Alberto Caprara Andrea Lodi Silvano Martello Michele Monaci 《Discrete Optimization》2006,3(4):317-326
We address the problem of packing a given set of rectangles into the minimum size square. We consider three versions of the problem, arising when the rectangles (i) are squares; (ii) have a fixed orientation; (iii) can be rotated by 90. For each case we study lower bounds, and analyze their worst-case performance ratio. In addition, we evaluate through computational experiments their average performance on instances from the literature. 相似文献
5.
In this paper we address a two-dimensional (2D) orthogonal packing problem, where a fixed set of small rectangles has to be placed on a larger stock rectangle in such a way that the amount of trim loss is minimized. The algorithm we propose hybridizes a placement procedure with a genetic algorithm based on random keys. The approach is tested on a set of instances taken from the literature and compared with other approaches. The computation results validate the quality of the solutions and the effectiveness of the proposed algorithm. 相似文献
6.
The nanogranular nature of C-S-H 总被引:6,自引:0,他引:6
Despite its ubiquitous presence as binding phase in all cementitious materials, the mechanical behavior of calcium-silicate-hydrates (C-S-H) is still an enigma that has deceived many decoding attempts from experimental and theoretical sides. In this paper, we propose and validate a new technique and experimental protocol to rationally assess the nanomechanical behavior of C-S-H based on a statistical analysis of hundreds of nanoindentation tests. By means of this grid indentation technique we identify in situ two structurally distinct but compositionally similar C-S-H phases heretofore hypothesized to exist as low density (LD) C-S-H and high density (HD) C-S-H, or outer and inner products. The main finding of this paper is that both phases exhibit a unique nanogranular behavior which is driven by particle-to-particle contact forces rather than by mineral properties. We argue that this nanomechanical blueprint of material invariant behavior of C-S-H is a consequence of the hydration reactions during which precipitating C-S-H nanoparticles percolate generating contact surfaces. As hydration proceeds, these nanoparticles pack closer to center on-average around two characteristic limit packing densities, the random packing limit (η=64%) and the ordered face-centered cubic (fcc) or hexagonal close-packed (hcp) packing limit (η=74%), forming a characteristic LD C-S-H and HD C-S-H phase. 相似文献
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El Houssaine Aghezzaf Thomas L. Magnanti Laurence A. Wolsey 《Mathematical Programming》1995,71(2):113-126
Given a treeG = (V, E) and a weight function defined on subsets of its nodes, we consider two associated problems. The first, called the rooted subtree problem, is to find a maximum weight subtree, with a specified root, from a given set of subtrees.The second problem, called the subtree packing problem, is to find a maximum weight packing of node disjoint subtrees chosen from a given set of subtrees, where the value of each subtree may depend on its root.We show that the complexity status of both problems is related, and that the subtree packing problem is polynomial if and only if each rooted subtree problem is polynomial. In addition we show that the convex hulls of the feasible solutions to both problems are related: the convex hull of solutions to the packing problem is given by pasting together the convex hulls of the rooted subtree problems.We examine in detail the case where the set of feasible subtrees rooted at nodei consists of all subtrees with at mostk nodes. For this case we derive valid inequalities, and specify the convex hull whenk 4.Research supported in part by Nato Collaborative Research Grant CRG 900281, Science Program SC1-CT91-620 of the EEC, and contract No 26 of the programme Pôle d'attraction interuniversitaire of the Belgian government. 相似文献
9.
Seymour (1981) proved that the cut criterion is necessary and sufficient for the solvability of the edge-disjoint paths problem when the union of the supply graph and the demand graph is planar and Eulerian. When only planarity is required, Middendorf and Pfeiffer (1993) proved the problem to be NP-complete. For this case, Korach and Penn (1992) proved that the cut criterion is sufficient for the existence of a near-complete packing of paths. Here we generalize this result by showing how a natural strengthening of the cut criterion yields better packings of paths.Analogously to Seymour's approach, we actually prove a theorem on packing cuts in an arbitrary graph and then the planar edge-disjoint paths case is obtained by planar dualization. The main result is derived from a theorem of Seb (1990) on the structure of ±1 weightings of a bipartite graph with no negative circuits.Research partially supported by the Hungarian National Foundation for Scientific Research Grants OTKA 2118 and 4271. 相似文献
10.
This paper introducesa novel method for packing Capillary Electrochromatography Columns (CEC). Using vacuum packing methodology, silica particles as small as 1 microm were successfully packed into the capillary columns with 75 microm inner diameter. The columns are verystable and show no noticeable loss in efficiency after 200 sample injections. The performance of these vacuum packed capillary columns was evaluated with a mixture of aromatic and non-aromatic compounds. A 24 cm long capillary column can produce peak efficiencies of around 45,000 plates for benzene. 相似文献