浆体管道输送水击压力波波速的探讨

 在考虑自由气体存在的影响下，推导出浆体水击压力波波速的 计算公式.分析表明很少量的气体存在会使波速明显降低. 气体体积 浓度较大时波速随浆体浓度的增大而减小，重质物料的减小趋势较 为明显；气体体积浓度较小时轻质物料波速随浓度的增加而增加. 相同条件下非均质流波速比伪均质流波速大，两者差异主要受浆体 中固体物料的密度和浆体体积浓度影响. 考虑气体影响作用的浆击 波速计算值与实测结果更吻合.     

衬底加热和电极修饰对提高有机场效应晶体管性能的影响

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.     

Synthesis, Crystal Structure, and Herbicidal Activities of 2-Cyanoacrylates Containing 1,3,4-Thiadiazole Moieties

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.     

Freight transportation in railway networks with automated terminals: A mathematical model and MIP heuristic approaches

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.     

Maritime inventory routing with multiple products: A case study from the cement industry

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.     

磁场对瓦斯爆炸及其传播的影响

为了弄清煤矿井下巷道中变电站、大型机电设备等产生较强的磁场对瓦斯爆炸的影响机理和影响程度,实验研究了外加磁场对瓦斯爆炸过程中爆炸应力波和火焰传播速度的影响,并从磁场影响瓦斯爆炸及其传播的传质、传热、反应过程等进行了理论分析.研究结果表明:外加磁场能增加瓦斯爆炸强度和火焰传播速度以及增大压力波超压峰值和火焰传播速度峰值,...     

智能交通系统的元胞自动机交通流模型

在Nagel-Schreckenberg(NS)模型的基础上，提出一种可应用智能交通系统（ITS）信息的新的交通流元胞自动机模型. 其中考虑了有效间距及刹车灯的作用，并引入了可变安全间距的新概念. 数值模拟表明：对于这种改进的ITS元胞自动机模型，道路交通量有了显著提高，体现了智能交通的优越性——有效地扩大交通流量，减少阻塞生成. 当考虑快车和慢车的混合交通流时，发现即使少量的慢车也会导致交通流量大幅度下降，说明了严格实施快慢道行驶的必要性. 关键词： 交通流 智能交通系统（ITS） 元胞自动机模型 刹车灯 可变安全间距     

THE SIMPLE BLOCK ITERATIVE ALGORITHM OF AN EXTENDED ENTROPY MODEL AND ITS CONVERGENCE

1.ExtendedEntropyModelEntropymodelsarewidelyusedasaforecastingtechniqueinregionalplanning,see11]and[7].Theydescribeinacertainwaythemostprobablespatialinteractionandcanbeusedtoestimateorigin-destinationtripmatrices.Butthemodelsaretoosimple,soitisdifficulttomeetpracticalrequirements.HallefjordandJo..stenl2]putforwardthegeneralizationofthestandardentropymodels.Onthebasisofthisandaccordingtothedemandofthepredictionofthetripamountfortransportationplanning,wearriveatthefollowing:wherep,μandnarepo…     

运输问题悖论及其研究

提出了运输问题的奇特现象——运输问题的悖论,讨论了运输问题悖论出现的条件,最后指出了研究运输问题悖论的现实意义.     

关于运输问题最优解的进一步讨论

首先给出了运输问题最优解的相关概念,将最优解扩展到广义范畴,提出狭义多重最优解和广义多重最优解的概念及其区别.然后给出了惟一最优解、多重最优解、广义有限多重最优解、广义无限多重最优解的判定定理及其证明过程.最后推导出了狭义有限多重最优解个数下限和广义有限多重最优解个数上限的计算公式,并举例验证了结论的正确性.