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41.
42.
Beautiful formulas are known for the expected cost of random two‐dimensional assignment problems, but in higher dimensions even the scaling is not known. In three dimensions and above, the problem has natural “Axial” and “Planar” versions, both of which are NP‐hard. For 3‐dimensional Axial random assignment instances of size n, the cost scales as Ω(1/ n), and a main result of the present paper is a linear‐time algorithm that, with high probability, finds a solution of cost O(n–1+o(1)). For 3‐dimensional Planar assignment, the lower bound is Ω(n), and we give a new efficient matching‐based algorithm that with high probability returns a solution with cost O(n log n). © 2013 Wiley Periodicals, Inc. Random Struct. Alg., 46, 160–196, 2015 相似文献
43.
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
44.
45.
引入差异度指标描述碎纸片图像边缘的匹配程度,以差异度最小为目标建立TSP问题的数学模型,并按照指派模型求解。设计“按行聚类-行内排序”算法,以降低算法的时间复杂度;同时,对字符进行聚类分析,并利用模式识别技术降低拼接的错误率,减少人工干预;通过纵切、纵横切、双面的中英文碎纸片的复原,验证了拼接模型和算法的准确性和有效性。 相似文献
46.
Toru Araki 《Discrete Applied Mathematics》2009,157(8):1677-1686
An L(p,q)-labeling of a graph G is an assignment f from vertices of G to the set of non-negative integers {0,1,…,λ} such that |f(u)−f(v)|≥p if u and v are adjacent, and |f(u)−f(v)|≥q if u and v are at distance 2 apart. The minimum value of λ for which G has L(p,q)-labeling is denoted by λp,q(G). The L(p,q)-labeling problem is related to the channel assignment problem for wireless networks.In this paper, we present a polynomial time algorithm for computing L(p,q)-labeling of a bipartite permutation graph G such that the largest label is at most (2p−1)+q(bc(G)−2), where bc(G) is the biclique number of G. Since λp,q(G)≥p+q(bc(G)−2) for any bipartite graph G, the upper bound is at most p−1 far from optimal. 相似文献
47.
K. Helios H. Maniak M. Sowa W. Zierkiewicz M. Wąsińska-Kałwa M. Giurg 《Journal of Coordination Chemistry》2017,70(20):3471-3487
The first metal complex of Phx-1 ligand, bis(2-amino-4,4α-dihydro-4α,7-dimethyl-3H-phenoxazin-3-one)nitratosilver(I), [Ag(Phx-1)2NO3], has been obtained and investigated by single crystal X-ray diffraction and vibrational spectroscopy methods. The Ag+ is bonded to heterocyclic nitrogen atoms of two organic ligands and one oxygen atom of a nitrate anion. The Phx-1 ligand coordination mode is supported by IR and Raman spectra, interpreted with the help of theoretical DFT studies. The antibacterial activity of the ligand and its Ag(I) complex as well as some reference compounds were screened against Gram-positive and Gram-negative bacteria, applying microdilution procedures. High sensitivity to the studied complex was found for Rhodococcus erythropolis and Bacillus licheniformis strains. Modified Phx-1 ligand preparation procedures are also presented. 相似文献
48.
Wayne E. Steinmetz 《Magnetic resonance in chemistry : MRC》2010,48(7):565-570
Granatin B, a complex ellagitannin extracted from pomegranate fruit, has two equilibrating isomers, form a and form b. A full ensemble of proton and carbon‐13 NMR methods over a wide range of temperature enabled a complete assignment of the more abundant isomer and showed it to be form b. This result is based on the NMR data for granatin alone and agrees with the previous determinations which were based on a combination of chemical methods and a partial assignment of the NMR spectra. The new NMR spectra also yield exchange rates for the hydroxyl protons as a function of temperature. A molecular model involving hydrogen bonding provides an explanation for the exchange data. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
49.
An assignment of the near-infrared bands in the 600–800 nm spectral region observed in magnetic circular dichroism (MCD)
spectra of high-spin ferrous haemoproteins is presented. The assignment is based on a relative energy level scheme for iron
d-electrons, a comparison of predicted and measured temperature dependences of MCD intensity, a sign of MCD bands and a group
theoretical analysis of allowed transitions. The proposed assignment is consistent with the ∼15-nm red shift of the ∼760 nm
band on breakage of the Fe-His bond in deoxy-myoglobin at low pH, with low-temperature photolysis experiments available for
CO complexes of several haemoproteins. In accordance with the observations, the intensity of the MCD bands for proteins with
a sulphur anion of cysteine as proximal haemligand (cytochrome P450 and chloroperoxidase) is predicted to be diminished by
at least one order of magnitude compared to that for proteins with an imidazole of a histidine as a protein-derived haemligand
(i.e. myoglobin, haemoglobin and horseradish peroxidase).
Received: 4 February 1997 / Accepted: 1 May 1997 相似文献
50.
An automated NMR chemical shift assignment algorithm was developed using multi-objective optimization techniques. The problem is modeled as a combinatorial optimization problem and its objective parameters are defined separately in different score functions. Some of the heuristic approaches of evolutionary optimization are employed in this problem model. Both, a conventional genetic algorithm and multi-objective methods, i.e., the non-dominated sorting genetic algorithms II and III (NSGA2 and NSGA3), are applied to the problem. The multi-objective approaches consider each objective parameter separately, whereas the genetic algorithm followed a conventional way, where all objectives are combined in one score function. Several improvement steps and repetitions on these algorithms are performed and their combinations are also created as a hyper-heuristic approach to the problem. Additionally, a hill-climbing algorithm is also applied after the evolutionary algorithm steps. The algorithms are tested on several different datasets with a set of 11 commonly used spectra. The test results showed that our algorithm could assign both sidechain and backbone atoms fully automatically without any manual interactions. Our approaches could provide around a 65% success rate and could assign some of the atoms that could not be assigned by other methods. 相似文献