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111.
112.
M. Bauer O. Golinelli 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,24(3):339-352
We study both numerically and analytically what happens to a random graph of average connectivity α when its leaves and their
neighbors are removed iteratively up to the point when no leaf remains. The remnant is made of isolated vertices plus an induced
subgraph we call the core. In the thermodynamic limit of an infinite random graph, we compute analytically the dynamics of leaf removal, the number
of isolated vertices and the number of vertices and edges in the core. We show that a second order phase transition occurs
at α = e = 2.718 ... : below the transition, the core is small but above the transition, it occupies a finite fraction of
the initial graph. The finite size scaling properties are then studied numerically in detail in the critical region, and we
propose a consistent set of critical exponents, which does not coincide with the set of standard percolation exponents for
this model. We clarify several aspects in combinatorial optimization and spectral properties of the adjacency matrix of random
graphs.
Received 31 January 2001 and Received in final form 26 June 2001 相似文献
113.
阐明狭义相对性原理的准确含义,批出它并不要求自然界每条定律都单独协变,但要求每条定律至少属于一个协变集合,给出最小协变集的求法。表明机械能守恒定律满足狭义相对性原理及其对自然界定律的协变性要求,还指出一切社会科学定律也都满足狭义相对性原理。 相似文献
114.
We consider the problem of approximating an optimal solution to a separable, doubly infinite mathematical program (P) with lower staircase structure by solutions to the programs (P(N)) obtained by truncating after the firstN variables andN constraints of (P). Viewing the surplus vector variable associated with theNth constraint as a state, and assuming that all feasible states are eventually reachable from any feasible state, we show that the efficient set of all solutions optimal to all possible feasible surplus states for (P(N)) converges to the set of optimal solutions to (P). A tie-breaking algorithm which selects a nearest-point efficient solution for (P(N)) is shown (for convex programs) to converge to an optimal solution to (P). A stopping rule is provided for discovering a value ofN sufficiently large to guarantee any prespecified level of accuracy. The theory is illustrated by an application to production planning.The work of Robert L. Smith was partially supported by the National Science Foundation under Grant ECS-8700836. 相似文献
115.
In this paper,we point out that several assertions(Propositions 3.15 and 5.2(v)) in a previous paper by Majumdar and Samanta are not true in general,by counterexamples. 相似文献
116.
FAN CuiLing LEI JianGuo & SHAN XiuLing School of Sciences Nantong University Nantong China College of Mathematics Information Science Hebei Normal University Shijiazhuang 《中国科学 数学(英文版)》2011,(1)
Difference systems of sets (DSSs) are combinatorial configurations which were introduced in 1971 by Levenstein for the construction of codes for synchronization. In this paper, we present two kinds of constructions of difference systems of sets by using disjoint difference families and a special type of difference sets, respectively. As a consequence, new infinite classes of optimal DSSs are obtained. 相似文献
117.
Jean-Pierre Planckaert El-Hadi Djermoune David Brie Francis Briand Frédéric Richard 《Applied Mathematical Modelling》2010
This paper investigates some issues in physical modeling of metal inert gas/metal active gas (MIG/MAG) welding process in the short arc mode. In this mode, a metal supply is molten in the arc state and then transferred to the weld pool during the short-circuit state. A hybrid model having two distinct continuous states whose switchings are controlled by two guard conditions is proposed. Due to the complexity of the physical phenomena involved in the welding process, simplifications are used to obtain a model accounting for the main physical contributions but simple enough to yield an efficient, fast and numerically tractable simulator which can be used intensively for evaluating different control strategies. In an attempt to validate the proposed model, different measurements have been made including supply voltage and current sampled synchronously with high speed digital video. In order to extract some relevant quantities representative of the metal transfer from image sequences, an active contour algorithm is developed and tested. The effectiveness of the proposed model in the prediction of major tendencies of a welding process, especially in the arc state, is shown using experimental data. Some limitations of the model during the metal transfer are also stressed and possible remedies are then proposed. 相似文献
118.
Treatment of chlorella green algae (Chlorella sp.) for 2 h in the dark with the photodynamic herbicide glutaphen (GTP), consisting
of 0.3 mM 1,10-phenanthroline and 0.6 mM glutamic acid, followed by illumination leads to efficient generation of active oxygen
species (AOS). After 15 min of illumination, AOS accumulation reaches 200% compared with the level in cells of the control
culture, then it decreases down to 130% and 115% after 1 day and 3 days of illumination. During the first few days after treatment,
we observe inhibition of synthesis of a specific precursor of chlorophyll (Chl): 5-aminolevulinic acid molecules, and then
we observe stimulation of the synthesis. The effect of GTP on the photosynthetic activity of chlorella does not depend on
the AOS level but rather remains uniform, in contrast to its effect on the Chl biosynthesis system. GTP does not change the
efficiency of light harvesting and charge separation at the reaction centers of photosystem (PS) 2, but significantly lowers
the functional efficiency of the electron transport chain: the photochemical quenching constants for Chl a fluorescence and
the effective quantum yield of photochemical reactions in photosystem 2 decrease. The major mechanism of action for GTP is
probably displacement of the secondary quinone acceptor QB from its binding site on the D1 protein by the 1,10-phenanthroline, consequent inhibition of electron efflux from Q
A
−
and increase in the fraction of QB-nonreducing centers of PS 2. The active oxygen species generated in the cells have a photodegradative effect on the Chl biosynthesis
system, in particular on its initial steps, and do not involve already formed pigment-protein complexes of PS 2.
__________
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 6, pp. 801–806, November–December, 2006. 相似文献
119.
智能交通系统可以实时反馈路况信息、诱导出行,进而缓解交通拥堵.在时间反馈和平均速度反馈两种信息服务策略下,考虑重叠路段的影响,利用元胞自动机模型对人们的路径选择行为进行了模拟.结果表明,在含有重叠路段的网络中,相对时间反馈策略而言,平均速度反馈策略可以更有效地降低人们的出行时间,其优势在重叠部分长度占路径长度的比例很小和较大时十分明显,且随路径长度的增加而上升.在提高路网的利用效率方面,平均速度反馈策略的优势随路径长度的增加而逐渐下降,随重叠部分长度的增加而先降后升.
关键词:
交通流
元胞自动机
智能交通系统
信息反馈策略 相似文献
120.