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91.
92.
图G的L(2,1)-标号是一个从顶点集V(G)到非负整数集的函数f(x),使得若d(z,y)=1则|f(x)-f(y)|≥2;若d(x,y)=2,则|f(x)-f(y)|≥1。图G的L(2,1)-标号数是λ(G)使得G有的max|f(v):v∈V(G)|=κ的L(2,1)-标号中的最小数κ。本将L(2,1)-标号问题推广到更一般的情形即L(3,2,1)标号问题,并得到了平面三角剖分图、立体四面体剖分图的λ3(G)的上界。 相似文献
93.
求解指派问题的一个算法 总被引:7,自引:0,他引:7
为了便于建立与指派问题有关的决策支持系统,本给出了一个求解指派问题的数值算法,证明了算法的理论依据。该算法能求得问题的最优解,并具有易于编程实现、收敛性好等优点,大量数值实验表明该算法非常实用有效。 相似文献
94.
Balinski uses his signature method for the proof of the Hirsch-conjecture for dual transportation polyhedra to obtain an efficient
algorithm for the assignment problem. We will show how to extend this method to other primal transportation problems, including
transportation problems with unit demands. We then prove that Balinski's assignment algorithm is equivalent, cycle by cycle,
to that of Hung and Rom. We demonstrate that, under some assumptions for our probability model, a modification of the latter
algorithm has an average complexity of O(n
2logn) and present some computational results confirming this. We also present results that indicate that this modification compares
favorably with Balinski's algorithm and other codes.
Research of both authors supported, in part, by grants of the Alexander von Humboldt-Stiftung.
Supported, in part, by NSF grant DMS-8504050. 相似文献
95.
Teng‐Shuo Zhang Rui Du Yan‐Yin Zhao Jia‐Dan Xue Hui‐Gang Wang Xuming Zheng 《Journal of Raman spectroscopy : JRS》2016,47(3):299-309
The B‐band resonance Raman spectra of 2(1H)‐pyridinone (NHP) in water and acetonitrile were obtained, and their intensity patterns were found to be significantly different. To explore the underlying excited state tautomeric reaction mechanisms of NHP in water and acetonitrile, the vibrational analysis was carried out for NHP, 2(1D)‐pyridinone (NDP), NHP–(H2O)n (n = 1, 2) clusters, and NDP–(D2O)n (n = 1, 2) clusters on the basis of the FT‐Raman experiments, the B3LYP/6‐311++G(d,p) computations using PCM solvent model, and the normal mode analysis. Good agreements between experimental and theoretically predicted frequencies and intensities in different surrounding environments enabled reliable assignments of Raman bands in both the FT‐Raman and the resonance Raman spectra. The results indicated that most of the B‐band resonance Raman spectra in H2O was assignable to the fundamental, overtones, and combination bands of about ten vibration modes of ring‐type NHP–(H2O)2 cluster, while most of the B‐band resonance Raman spectra in CH3CN was assigned to the fundamental, overtones, and combination bands of about eight vibration modes of linear‐type NHP–CH3CN. The solvent effect of the excited state enol‐keto tautomeric reaction mechanisms was explored on the basis of the significant difference in the short‐time structural dynamics of NHP in H2O and CH3CN. The inter‐molecular and intra‐molecular ESPT reaction mechanisms were proposed respectively to explain the Franck–Condon region structural dynamics of NHP in H2O and CH3CN.Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
96.
Single nucleotide polymorphisms of mitochondrial DNA HVS‐I and HVS‐II in Chinese Bai ethnic group
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Feng Chen Cai‐Yong Yin Xiao‐Qin Qian Han‐Ting Fan Ya‐Jun Deng Yu‐Dang Zhang Hao‐Tian Meng Chun‐Mei Shen Chun‐Hua Yang Rui Jin Bo‐Feng Zhu Peng Xu 《Electrophoresis》2015,36(6):930-936
For forensic and population genetic purposes, a total of 125 unrelated volunteers’ blood samples were collected from Chinese Bai ethnic minority group to analyze sequence variation of two hypervariable segments (HVS‐I and HVS‐II) in the mitochondrial DNA control region. Comparing the HVS‐I and HVS‐II sequences of the 125 Chinese Bais to the Anderson reference sequence, we found 86 polymorphic loci in HVS‐I and 40 in HVS‐II in mitochondrial DNA sequences of the Chinese Bai ethnic minority group, which defined 93 and 53 different haplotypes, respectively. Haplotype diversity and the mean pairwise differences were 0.992 ± 0.003 and 6.553 in HVS‐I, and 0.877 ± 0.027 and 2.407 in HVS‐II, respectively. We defined four macrohaplogroups R, M, N and D with the proportions ranging from 9.6% to 40.0%. With the analysis of the hypervariable domain from nucleotide 16 180–16 193 in HVS‐I, our study revealed new haplotypes of sequence variations. In addition, the Fst metric, phylogenetic tree, and principal component analysis demonstrated a close genetic relationship between the Bai group and Chinese Han populations from South China, Changsha, and Guangdong. The results support that the Bai group is a multiorigin ethnic minority that has merged with the Chinese Han population. 相似文献
97.
Barium calcium magnesium silicate (BaCa2MgSi2O8), a compound whose space group was obtained via X-ray diffraction data, was re-investigated using neutron diffraction techniques. A combined powder X-ray and neutron Rietveld method revealed that BaCa2MgSi2O8 crystallizes in the trigonal space group P3? (Z=1, a=5.42708(5) Å, c=6.79455(7) Å, V=173.310(4) Å3; Rp/Rwp=5.52%/7.63%), instead of the previously believed space group P3?m1. The difference in the two structures arises from the displacement of the O2 atom. Blue emission from Ba0.98Eu0.02Ca2MgSi2O8 under 325-nm excitation is ascribed to the 4f65d1→4f7 transitions of Eu2+ ions at Ba sites and Ca sites. Site assignment of Eu2+ ions in the titled compound was performed by analysis of emission spectra at temperatures in the range of 4.2-300 K. 相似文献
98.
地震期间应急资源调度方案的优化选取 总被引:1,自引:0,他引:1
应急资源的调度是地震救援工作的重点,为解决这个难题,本文构建了以时效性、伤亡性和经济性为三大分量的多目标函数,然后经过无量纲和Delphi加权处理,将其转化为单目标函数,并将其中的决策效用函数看成运筹学中指派问题的效率函数,最后运用匈牙利法计算出最大的目标函数值,从而得出最优的资源调度方案.与其他多目标的应急资源调度方法相比,本文构建的这种算法具有简易、实用的优点,可以说为地震期间应急资源调度方案的优化选取工作提供了一种切实、可行的途径. 相似文献
99.
Global optimization of a class of nonconvex quadratically constrained quadratic programming problems
Yong Xia 《数学学报(英文版)》2011,27(9):1803-1812
In this paper we study a class of nonconvex quadratically constrained quadratic programming problems generalized from relaxations
of quadratic assignment problems. We show that each problem is polynomially solved. Strong duality holds if a redundant constraint
is introduced. As an application, a new lower bound is proposed for the quadratic assignment problem. 相似文献
100.
本文研究了机场任务指派问题,该问题是指将具有特殊属性的任务指派给有限数量的班次。由于机场任务和班次属性的多样性,机场任务指派问题是一个复杂的组合优化问题,属于NP-完全问题。本文以任务完成产生的效益总和最大化为目标建立数学优化模型,提出有效不等式,应用CPLEX软件对实际数据进行求解,结果表明,CPLEX可以在较短时间内对一定规模的算例求得最优解。同时对影响目标函数的四个因素:任务数量、班次数量、班次工作时长和任务属性分别进行分析,通过实际算例测试对比,得出具有指导意义的结论,即根据机场特征分别调整四个因素不仅能够提高机场资源的有效利用率,而且能够提高机场的运行效率和服务水平。 相似文献