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361.
Production and space-time evolution of heavy quarks in central and non-central heavy-ion collisions at RHIC and LHC are studied with the partonic transport model Boltzmann Approach of MultiParton Scatterings (BAMPS). In addition to the initially created heavy quarks in hard parton scatterings during nucleon-nucleon collisions, secondary heavy quark production in the quark-gluon plasma is investigated and the sensitivity on various parameters is estimated. In BAMPS heavy quarks scatter with particles of the medium via elastic collisions, whose cross section is calculated with the running coupling and a more precise implementation of Debye screening. In this framework, we compute the elliptic flow and nuclear modification factor of heavy quarks and compare it to the experimental data. 相似文献
362.
363.
引用两种加速计算PageRank的算法,分别为内外迭代法和两步分裂迭代算法.从这两种方法中,得到多步幂法修正的内外迭代方法.首先,详细介绍了算法实施过程.然后,对此算法的收敛性进行证明,并且将此算法的谱半径与两步分裂迭代算法的谱半径进行比较.最后,数值试验说明该算法的计算速度比两步分裂迭代法要快. 相似文献
364.
利用复变函数方法和积分方程理论研究了既含有圆形孔口又含有水平裂纹的无限大平面的平面弹性问题,将复杂的解析函数的边值问题化成了求解只在裂纹上的奇异积分方程的问题.此外,还给出了裂纹尖端附近的应力场和应力强度因子的公式. 相似文献
365.
以建筑工程为研究对象,选取13项影响建筑工程质量因素的指标,运用解释结构模型(ISM)系统分析各因素之间的内在联系,并在此基础上建立4级多层次递阶结构模型,进一步精确描述各因素间的直接关系,从而直观地反映各因素间的层级关系及相互影响,并找到了影响建筑工程质量的根本原因,进而为改善我国建筑工程质量提供一定的参考依据. 相似文献
366.
Vojtech Blint 《Journal of Discrete Algorithms》2003,1(3-4):339-355
Let G be an undirected graph with two edge costs (c-cost and d-cost). We want to minimize the diameter of a spanning subgraph S (under d-cost) subject to the constraint that the total cost of the edges in S (with respect to c) does not exceed a given budget. We prove that this problem is non-approximable, even in some special cases. Similar results are proved if the stretch factor or the root stretch factor is considered instead of the diameter. 相似文献
367.
1前言压缩因子是比较实际气体与理想气体之差异的重要物理量,从某状态的压缩因子Z可求出该状态下实际气体的P或V来。现在高压气体的Z大多是在高压PVT实验台上用定容测试方法(绝对法)测试出来。但测试过程耗时费资,在新型气态工质不断涌现的今天,一些特殊高压高温条件很难在实验中满足;而工程上则多从对比态原理出发,从两参量或三参量的普遍化压缩因子图中近似求出,显然,其系统误差一般较大,一般说来,高压气体的Z是系统温度T,压力P和偏心因子。的函数Z=Z(T,P),其解析形式一直是热物性工作者努力探求的目标,… 相似文献
368.
A proposed structure for the diffusible extracellular factor (DF) of Xanthomonas campestris pv. campestris (Xcc) has been synthesized. Its MS spectrum and biological activity, however, contradict those of the natural product previously reported, suggesting that the structure for DF of Xcc must be reexamined. 相似文献
369.
An integrated model for ranking scientific publications together with authors and journals recently presented in [Bini, Del Corso, Romani, ETNA 2008] is closely analyzed. The model, which relies on certain adjacency matrices H,K and F obtained from the relations of citation, authorship and publication, provides the ranking by means of the Perron vector of a stochastic matrix obtained by combining H,K and F. Some perturbation theorems concerning the Perron vector previously introduced by the authors are extended to more general cases and a counterexample to a property previously addressed by the authors is presented. The theoretical results confirm the consistency and effectiveness of our model. Some paradigmatic examples are reported together with some results obtained on a real set of data. 相似文献
370.
With the finite element method and the limit equilibrium method, a numerical model has been established for examining the
effects of rainfall infiltration on the stability of slopes. This model is able to availably reflect the variations in pore
pressure field in slopes, dead weight of soil, and the softening of soil strength caused by rainfall infiltration. As a case
study, an actual landslide located at the Nongji Jixiao in Chongqing is studied to analyze the effects of rainfall infiltration
on the seepage field and the slope stability. The simulated results show that a deep slope failure is prone to occur when
rainfall infiltration will lead to a remarkable variation in the seepage field, in particular, for large range pore water
pressure increase in slopes.
Supported by the Knowledge Innovation Project of Chinese Academy of Sciences (Grant No. KJCX2-SW-L1-4) and the Major State
Basic Research Development Program of China (Grant No. 2002CB412703) 相似文献