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It is well-known that exact branch and bound methods can only solve small or moderately sized ????-hard combinatorial optimization problems. In this paper, we address the issue of embedding an approximate branch and bound algorithm into a local search framework. The resulting heuristic has been applied to the problem of finding a minimum makespan in the permutation flow shop problem. Computational experiments carried out on a large set of benchmark problems show that the proposed method consistently yields optimal or near-optimal solutions for instances with up to 200 jobs and 10 machines. In particular, for 19 instances, the heuristic produces solutions that outperform the best known ones. 相似文献
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AbstractNew allelochemicals were identified through bio-guided fractionation from the ethyl acetate of seeds extracts, which was the most autotoxic compared to the other plant parts. Phytochemical investigation of the seeds extracts of C. arabica by spectroscopy analyses has led to identify two new dammarane type triterpenes (4 and 9), with nine known analogues (1???3, 5???8, 10 and 11), a new cucurbitane triterpene (12), acylated dehydrodiconiferyl alcohol (13), and three highly oxygenated flavonols (14?16). The most autotoxic compounds on germination and seedling growth were elucidated as dammarane type triterpenes. However, less autotoxic effect was recorded by an inhibition under 50% for most of the identified flavonoids. These results suggest that those autotoxic substances may be used as a new bio-herbicide that may contribute to manage the distribution of C. arabica in agronomic field. 相似文献
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Adnan A. S. Elkhaldy Dnyaneshwar Gaikwad Richard J. Staples Afef Janen Yannic Boni 《Phosphorus, sulfur, and silicon and the related elements》2013,188(12):871-876
AbstractO, O’-Dialkyl and alkylene dithiophosphatogold (III)dichloride complexes of the type [(RO)2PS2]AuCl2 and [S2POGO]AuCl2, where R?=?Et, nPr, iPr, iBu, Ph, cyclohexyl and cyclopentyl, where G?=?CMe2CMe2-, have been synthesized in 80-90% yields by reaction of the corresponding acid or sodium salts of the appropriate dithiophosphoric acids in 1:1 ratio with gold (III) chloride in dry dichloromethane at room temperature. The compounds have been characterized by elemental analyses, IR and (1H, l3C, and 31P) NMR. The crystal structure of [S2POCMe2CMe2O]AuCl2, was determined. These new complexes have shown their growth inhibiting potential against various bacterial strains with moderate to good activity. 相似文献
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In this Note, we consider the problem of the existence of conformal metrics with prescribed scalar curvature on the standard sphere , . We give new existence and multiplicity results based on a new Euler–Hopf formula type. Our argument also has the advantage of extending the well known results due to Y. Li (1995) [10]. 相似文献