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41.
分析循环取货模式和协同运输问题的关联性,提出了供需节点分离下的多车场一体化协同运输路线优化问题,考虑运输价值和运输成本,引入节点-弧流量的概念,通过比较流量大小确定节点集合,构建了问题的多供应点、多需求点运输模型.考虑取货的单向性和送货的闭合性,构造了求解模型的两阶段算法,运用动态规划的递推解法确定取货最优路线,然后基于余弦定理的几何法求解出发点和返回点不相同的送货路径优化问题,最后通过算例分析,说明了模型的合理性和算法的有效性. 相似文献
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随着社会经济的发展及人们环保意识的不断增强,公共交通事业的发展及其投资力度不断加大,公共交通在给人们带来方便的同时也在带动着经济的发展.通过扩展的生产函数模型,采用普通最小二乘方法对2003-2012年间的公共交通数据进行估计分析,并找出有异常值的样本点,然后利用稳健MM估计方法进行估计,结果表明公共交通变量对经济的影响具有正相关作用. 相似文献
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通过衬底加热和氧化钼(MoO3)修饰源漏极制备了并五苯有机场效应晶体管.研究了衬底温度和电极修饰层厚度对器件性能的影响.实验结果表明:当衬底温度为60℃、MoO3修饰层为10 nm时,器件性能获得了显著增强,场效应迁移率由原来的3.39×10-3 cm2/(V·s)提高到2.25 ×10-1 cm2/(V·s),阈值电压由12 V降低到3V.器件性能的改善归因于:衬底加热可以优化有源层形貌,改善载流子传输;而MoO3修饰层显著降低了电极与有源层之间的接触势垒,提高了载流子的注入.因此,衬底加热与电极修饰对于制备高性能有机场效应晶体管是不可或缺的优化手段. 相似文献
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Synthesis, Crystal Structure, and Herbicidal Activities of 2-Cyanoacrylates Containing 1,3,4-Thiadiazole Moieties 总被引:1,自引:0,他引:1
Tingting Wang Wenke Miao Shanshan Wu Guifang Bing Xin Zhang Zhenfang Qin Haibo Yu Xue Qin Jianxin Fang 《中国化学》2011,29(5):959-967
Three series of novel 2‐cyanoacrylates 7a – 7f , 9a – 9f , 10a – 10f containing 1,3,4‐thiadiazole ring moieties were synthesized as herbicidal inhibitors of photosystem II (PS II) electron transportation. Their structures were clearly verified by 1H NMR, 13C NMR, elemental analysis (or HRMS analysis) and single‐crystal X‐ray diffraction analysis. Bioassay showed that a suitable group at the 3‐position of acrylates was essential for high herbicidal activity. In particular, compound 7e showed the best herbicidal activities and gave 100% inhibitory activity against rape and amaranth pigweed at a dose of 1.5 kg/ha. Introduction of substituent with higher polarity such as sulfinyl or sulfonyl to the 5‐position of 1,3,4‐thiadiazole decreased herbicidal activities. 相似文献
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D. AnghinolfiM. Paolucci S. SaconeS. Siri 《European Journal of Operational Research》2011,214(3):588-594
In this paper we propose a planning procedure for serving freight transportation requests in a railway network with fast transfer equipment at terminals. We consider a transportation system where different customers make their requests (orders) for moving boxes, i.e., either containers or swap bodies, between different origins and destinations, with specific requirements on delivery times. The decisions to be taken concern the route (and the corresponding sequence of trains) that each box follows in the network and the assignment of boxes to train wagons, taking into account that boxes can change more than one train and that train timetables are fixed.The planning procedure includes a pre-analysis step to determine all the possible sequences of trains for serving each order, followed by the solution of a 0-1 linear programming problem to find the optimal assignment of each box to a train sequence and to a specific wagon for each train in the sequence. This latter is a generalized assignment problem which is NP-hard. Hence, in order to find good solutions in acceptable computation times, two MIP heuristic approaches are proposed and tested through an experimental analysis considering realistic problem instances. 相似文献
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Marielle Christiansen Kjetil Fagerholt Truls Flatberg Øyvind Haugen Oddvar Kloster Erik H. Lund 《European Journal of Operational Research》2011
This paper considers a maritime inventory routing problem faced by a major cement producer. A heterogeneous fleet of bulk ships transport multiple non-mixable cement products from producing factories to regional silo stations along the coast of Norway. Inventory constraints are present both at the factories and the silos, and there are upper and lower limits for all inventories. The ship fleet capacity is limited, and in peak periods the demand for cement products at the silos exceeds the fleet capacity. In addition, constraints regarding the capacity of the ships’ cargo holds, the depth of the ports and the fact that different cement products cannot be mixed must be taken into consideration. A construction heuristic embedded in a genetic algorithmic framework is developed. The approach adopted is used to solve real instances of the problem within reasonable solution time and with good quality solutions. 相似文献
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