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表面粗糙度对有机玻璃材料真空沿面闪络特性的影响  [PDF]
郎艳,王艺博,苏国强,宋佰鹏,穆海宝,张冠军
高电压技术 , 2015, DOI: 10.13336/j.1003-6520.hve.2015.02.017
Abstract: 目前国内外关于绝缘材料的表面粗糙度对其真空中沿面闪络特性的影响尚无定论。为此以有机玻璃材料为研究对象,采用不同目数的砂纸制备不同表面粗糙度的样品,并进行了真空沿面闪络实验研究。结果表明随着表面粗糙度的增加,有机玻璃的闪络电压呈现U型变化规律,即先减小后增大的变化趋势。同时,研究了打磨方向对有机玻璃闪络特性的影响。在粗糙度较大的情况下,合适的打磨方向可以明显提高闪络电压,尤其是垂直于电极方向打磨时,材料表现出闪络电压高、分散性小的特点;但在粗糙度较小的范围内,闪络特性受打磨方向的影响不明显,甚至有略微下降的趋势。结合实验结果,基于二次电子发射雪崩理论,从宏观和微观2个角度讨论了粗糙度对于绝缘材料闪络特性的影响机理,提出了表面粗糙度对于闪络影响的博弈模型。
Spanning trees and Khovanov homology  [PDF]
Abhijit Champanerkar,Ilya Kofman
Mathematics , 2006,
Abstract: The Jones polynomial can be expressed in terms of spanning trees of the graph obtained by checkerboard coloring a knot diagram. We show there exists a complex generated by these spanning trees whose homology is the reduced Khovanov homology. The spanning trees provide a filtration on the reduced Khovanov complex and a spectral sequence that converges to its homology. For alternating links, all differentials on the spanning tree complex are zero and the reduced Khovanov homology is determined by the Jones polynomial and signature. We prove some analogous theorems for (unreduced) Khovanov homology.
Uniform random spanning trees  [PDF]
Robin Pemantle
Mathematics , 2004,
Abstract: There are several good reasons you might want to read about uniform spanning trees, one being that spanning trees are useful combinatorial objects. Not only are they fundamental in algebraic graph theory and combinatorial geometry, but they predate both of these subjects, having been used by Kirchoff in the study of resistor networks. This article addresses the question about spanning trees most natural to anyone in probability theory, namely what does a typical spanning tree look like?
Packing of Rigid Spanning Subgraphs and Spanning Trees  [PDF]
Joseph Cheriyan,Olivier Durand de Gevigney,Zoltán Szigeti
Computer Science , 2012,
Abstract: We prove that every (6k + 2l, 2k)-connected simple graph contains k rigid and l connected edge-disjoint spanning subgraphs. This implies a theorem of Jackson and Jord\'an [4] and a theorem of Jord\'an [6] on packing of rigid spanning subgraphs. Both these results are generalizations of the classical result of Lov\'asz and Yemini [9] saying that every 6-connected graph is rigid for which our approach provides a transparent proof. Our result also gives two improved upper bounds on the connectivity of graphs that have interesting properties: (1) every 8-connected graph packs a spanning tree and a 2-connected spanning subgraph; (2) every 14-connected graph has a 2-connected orientation.
考虑磁场闪络抑制效应的真空绝缘堆闪络概率计算  [PDF]
李逢,王勐,王传伟,何勇,陈林,邹文康
强激光与粒子束 , 2011,
Abstract: ?基于统计学闪络经验公式,计算绝缘堆闪络概率,结果显示:绝缘堆电压峰值越低、电压有效作用时间越短、材料常数越小,则闪络概率越低;在一定绝缘堆电压范围内,绝缘堆半径越小,闪络概率越低。考虑磁场闪络抑制效应,计算了绝缘堆闪络概率。通过电场强度与磁感应强度之比得到磁场开始闪络抑制作用的临界比值。根据绝缘体与电极的夹角以及阴极三相点电场强度与平均电场强度的关系,得到不同的临界比值,比较闪络概率计算结果的差异。计算结果表明:在磁场闪络抑制效应作用下,绝缘堆闪络概率下降。
Spanning trees on the Sierpinski gasket  [PDF]
Shu-Chiuan Chang,Lung-Chi Chen
Statistics , 2006, DOI: 10.1007/s10955-006-9262-0
Abstract: We obtain the numbers of spanning trees on the Sierpinski gasket $SG_d(n)$ with dimension $d$ equal to two, three and four. The general expression for the number of spanning trees on $SG_d(n)$ with arbitrary $d$ is conjectured. The numbers of spanning trees on the generalized Sierpinski gasket $SG_{d,b}(n)$ with $d=2$ and $b=3,4$ are also obtained.
超微粉碎工艺通心络胶囊治疗中风病的临床研究  [PDF]
吴以岭,李涛,李妍,李家康,胡国恒,谷春华,高学东
中国中药杂志 , 2007,
Abstract: 目的:评价超微粉碎工艺的通心络胶囊治疗中风病(气虚血瘀络阻型)的临床疗效和安全性。方法:采用随机、双盲、不同工艺不同剂量平行对照的非劣效性试验设计方法,选择病程在2周以上3个月以内、神经功能缺损评分为8~30分、总的生活能力评分在2~5级的中风病恢复期患者144例,其中试验组72例,对照组72例。试验组服用超微粉碎工艺的通心络胶囊,规格每粒0.26g,1次4粒,1日3次;对照组服用普通粉碎工艺的通心络胶囊,规格每粒0.38g,1次4粒,1日3次;疗程28d。结果:中风病综合疗效,试验组与对照组总有效率分别为91.3%和87.3%,两组比较差异无统计学意义。两组总有效率差值的95%可信区间下限为-4.57%,大于预设的非劣效性界值-15%,非劣效性检验合格。试验期间发生3例不良反应,其中试验组1例,对照组2例。结论:超微粉碎工艺的通心络胶囊对于气虚血瘀络阻型中风病患者疗效确切,与普通粉碎工艺的通心络胶囊疗效相当,且服用安全。
Orderly Spanning Trees with Applications  [PDF]
Yi-Ting Chiang,Ching-Chi Lin,Hsueh-I Lu
Computer Science , 2001, DOI: 10.1137/S0097539702411381
Abstract: We introduce and study the {\em orderly spanning trees} of plane graphs. This algorithmic tool generalizes {\em canonical orderings}, which exist only for triconnected plane graphs. Although not every plane graph admits an orderly spanning tree, we provide an algorithm to compute an {\em orderly pair} for any connected planar graph $G$, consisting of a plane graph $H$ of $G$, and an orderly spanning tree of $H$. We also present several applications of orderly spanning trees: (1) a new constructive proof for Schnyder's Realizer Theorem, (2) the first area-optimal 2-visibility drawing of $G$, and (3) the best known encodings of $G$ with O(1)-time query support. All algorithms in this paper run in linear time.
On the Number of Incipient Spanning Clusters  [PDF]
Michael Aizenman
Physics , 1996, DOI: 10.1016/S0550-3213(96)00626-8
Abstract: In critical percolation models, in a large cube there will typically be more than one cluster of comparable diameter. In 2D, the probability of $k>>1$ spanning clusters is of the order $e^{-\alpha k^{2}}$. In dimensions d>6, when $\eta = 0$ the spanning clusters proliferate: for $L\to \infty$ the spanning probability tends to one, and there typically are $ \approx L^{d-6}$ spanning clusters of size comparable to $|\C_{max}| \approx L^4$. The rigorous results confirm a generally accepted picture for d>6, but also correct some misconceptions concerning the uniqueness of the dominant cluster. We distinguish between two related concepts: the Incipient Infinite Cluster, which is unique partly due to its construction, and the Incipient Spanning Clusters, which are not. The scaling limits of the ISC show interesting differences between low (d=2) and high dimensions. In the latter case (d>6 ?) we find indication that the double limit: infinite volume and zero lattice spacing, when properly defined would exhibit both percolation at the critical state and infinitely many infinite clusters.
Spanning trees with nonseparating paths  [PDF]
Cristina G. Fernandes,César Hernández-Vélez,Orlando Lee,José C. de Pina
Mathematics , 2014,
Abstract: We consider questions related to the existence of spanning trees in graphs with the property that after the removal of any path in the tree the graph remains connected. We show that, for planar graphs, the existence of trees with this property is closely related to the Hamiltonicity of the graph. For graphs with a 1- or 2-vertex cut, the Hamiltonicity also plays a central role. We also deal with spanning trees satisfying this property restricted to paths arising from fundamental cycles. The cycle space of a graph can be generated by the fundamental cycles of any spanning tree, and Tutte showed, that for a 3-connected graph, it can be generated by nonseparating cycles. We are also interested in the existence of a fundamental basis consisting of nonseparating cycles.
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