基于需求分级的两次应急资源运输研究

为提高应急运输管理中物资运输的效率,在将物资需求分为两级的基础上,设计了两次运输模式,建立以首次输送时间最小和两次总输送时间最小为目标的双目标运输分配模型,并应用多目标遗传算法NSGAII设计算法.给出了一个具有代表性的算例,算例结果及其分析表明两次运输分配模型和遗传算法的有效性.     

基于改进烟花算法的中俄商品多式联运路径优化

中俄双边贸易随着"一带一路"倡议的深入落实呈现出稳定增长的态势,商品需求量的增多以及需求时间的多样化使得商品运输方式发生了重大转变,运输方式由原来的单一运输转变为现在的多式联运.通过多式联运构建综合交通运输方案,既能够满足商品需求量的激增以及商品需求时间的多样化,同时又能够发挥不同运输方式之间的优势,形成优势互补.为了求解多式联运物流路径优化问题,本文以中俄贸易区间的运输路线与运输方式为研究对象,综合考虑中俄贸易区间的商品种类、需求特点以及运输方式,建立了以运输成本、运输时间、碳排放量为优化目标的多目标优化模型.针对中俄贸易实际运输情况,本文仅考虑公、铁、海3种运输方式之间的多式联运,同时针对所构建模型的随机性和隐并行性,设计了求解该模型的改进烟花算法(improved FWA).通过以中俄两国之间的多品类商品运输为例进行算例分析,获得了多式联运运输路线的Pareto非劣解以及相应的运输成本、运输时间和碳排放量,并且与基本烟花算法进行对比,验证了模型和改进算法的有效性.同时,本文以运输时间作为灵敏度分析变量,分析不同时间需求下,运输方案在运输成本、运输时间和碳排放量3个属性之间的变动趋...     

考虑模糊需求的多式联运路径优化

多式联运可有效降低物流成本,提高物流效率.本文构建了基于运量不确定的多式联运网络规划,以节点作业时间窗和运输时限客户满意度为约束,建立了以总费用最低为目标的多式联运路径优化模型,从运输路径和运输方式两个维度选择广义最短路径.应用Lingo 12.0实现模型的求解,实验结果表明了多式联运相较单一运输方式在运输时间与费用上的优越性,并应用灵敏度分析法,对比了仅考虑运输时限约束时客户满意度的变化,展示了运量的不确定性及运输弧与节点能力对路径规划产生的影响,揭示了客户满意度、网络能力、运输路径与费用等因素的相互关系,验证了所建模型的合理性.     

基于MOP模型的ITS对城市交通运输效率的优化研究

智能交通系统(ITS)作为协调各种交通方式和改善运输效率的主要途径,受众多因素影响导致应用效益折减,如何根据交通实际需求,凝练ITS优化运输效率的方案是ITS发展面临的重大任务.通过明确ITS对交通运输效率优化的目标和影响因素,以不同交通方式客运周转量为主要指标,构建ITS优化城市交通运行效率的多目标规划模型(MOP模型),并以北京市为例进行实证.研究结果显示,ITS是不同交通方式达到预期目标的支撑,并基于此提出了在保证交通运行效率最优时各交通方式完成的目标客运周转量.     

基于需求分级的两次应急资源运输研究

为提高应急运输管理中物资运输的效率,在将物资需求分为两级的基础上,设计了两次运输模式,建立以首次输送时间最小和两次总输送时间最小为目标的双目标运输分配模型,并应用多目标遗传算法NSGAII设计算法。最后,给出了一个具有代表性的算例,算例结果及其分析表明两次运输分配模型和遗传算法的有效性。     

运河航速限制情景下的班轮燃油补给决策与航速优化

为解决班轮运输船舶选择哪个港口进行燃油补给、燃油补给量以及各航段最优航速的问题,考虑船舶通过运河时对航速的影响与到港时间窗限制,建立以总成本最小为目标的燃油补给与航速优化模型.选择实际班轮航线进行算例分析,结果验证了模型的有效性.将考虑运河航速影响与不考虑运河航速影响的优化结果进行对比发现,考虑运河对航速影响时解得的燃油补给港选择、燃油补给量以及各航段最优航速的优化结果与客观实际相符,且有助于最小化航运企业总成本,表明该方法有助于航运企业结合航线实际情况合理地制定燃油补给决策以及航速优化方案,保障运输服务.     

基于概率有向图模型的船舶进出港航路规划

为降低港口水域内的船舶航行风险,提高港口生产效率,提出基于概率有向图模型的船舶进出港航路规划算法.采用基于密度的聚类方法,对船舶进出港的历史轨迹进行分类,从而提取出船舶在港内的正常航行模式,并采用基于网格划分的方法对轨迹进行离散.以网格为节点及相邻网格为有向边,建立概率有向图模型.给定航路的起始点和目的地,动态搜索船舶可能的航行路径进行航路规划.分别选取100条进港轨迹和100条出港轨迹对模型进行验证,结果表明:模型输出的进港规划航路与船舶真实航迹间的平均航路偏差为0.18,出港规划航路与真实航迹间的航路偏差为0.28.本模型生成的航路结合了多数船舶的进出港航行规律,其适航性能满足要求.     

基于多目标优化的渔获物冷链配送

远洋渔获物从港口出发被运输至各个需求市场的过程中,冷链配送方案的规划对于提高运输效率与降低成本投入等方面都起着至关重要的作用.为了提升配送效率和降低配送成本,根据渔获物受配送时间和环境温度等影响发生不同程度耗损的特点,引入低温能耗与需求时间窗等成本要素,建立了以配送服务时间最短和成本最小为目标的多目标冷链配送模型.根据所建立模型的决策变量,设计相应的遗传算法求解并结合某港口配送中心的算例进行分析.结果表明:本文提出的冷链物流配送模型可以为企业实现较少配送时间与较低成本,进而验证了模型的可行性.     

新冠疫情和双碳战略背景下班轮运输多目标优化

针对新冠疫情与"双碳战略"背景下的航线配船和货物分配问题,为满足班轮公司对船队运输效率、经济效益、服务质量和环保效益平衡发展的要求,以船队平均舱位利用率和营运利润最大以及货物时间价值损失与单箱碳排放量最小为目标,建立班轮航线配船与货物分配多目标优化模型.根据子问题间的内在联系,将模型分解为双层模型,上层采用混合整数非线...     

基于排队论的港口运输装卸服务系统优化方法研究

直接用汽车将集装箱运往港口堆场是集装箱货物运输的一种重要方式.在货物由内陆地区货运站到港口码头堆场的运输工作中,运输车辆与装卸机械是构成港口运输装卸服务系统最基本的生产要素.为减少运输车辆和装卸机械在运输生产过程中由于等待而产生的非生产停歇时间,控制车辆的等待费用和机械的装卸费用,获得最好的系统效率和生产效益,必须合理组织装卸机械和运输车辆的协调配合工作.在集装箱运输组织和管理中,运输车辆与装卸机械协调配合下装卸机械数量的确定,通常采用在一个连续和足够大的时问内以运输车辆和装卸机械两方面工作节奏相一致为条件进行建模的方法求解.这种方法存在的问题是车辆的周转时间和装卸停歇时间均采用平均值来计算,没有充分考虑车辆到达和装卸时间随机性的影响.本文运用排队论的理论方法,在建立港口运输装卸服务排队系统基础上,根据装卸机械数与等待费用和服务费用的变动关系,以系统在单位时间内承担的总费用最小作为决策目标来确定装卸机械的数量.以此实现运输车辆与装卸机械的协调配合,最终达到提高生产效率和效益、增强港口竞争力的目的.由于充分考虑了运输车辆运行时间和装卸机械装卸时间的随机性,因此该决策更具有科学性和合理性.     

An Index mechanism for multi-scale view in spatial databases

There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.     

Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3～4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰～ -7.8‰, PDB) and matrix dolomites (-6.6‰～ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084～0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078～0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.     

A computer generator for randomly layered structures

AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…     

Perspherical Approaches for Electrons in Atoms and Charged Excitons in Quantum Wells

Instead of following Fock’s expansion,we solve the Schrodinger equation for some quantum mechanical manybody systems such as electrons in atoms and charged excitons in quantum wells in a similar way in hyperspherical coordinates by expanding the wave functions into orthonormal complete basis sets of the hyperspherical hannonics(HHs)of hyperangles and generalized Laguerre polynomials(GLPs)of the hyperradius.This leads the equation to     

Advances in broadband wireless communications under high-mobility scenarios

Future mobile communication systems aim at providing very high data transmission rates, even in high-mobility scenarios such as high-speed wheel-track trains, maglev trains, highway vehicles, airplanes, guided missiles or spacecraft. A particularly important commercial application is the strong and increasing worldwide demand for high- speed broadband wireless communications （up to 574.8 km/ h test speeds or 380 km/h commercial speeds） in railways, providing data, voice and video services for applications such as onboard entertainment services to passengers, train control, train dispatch, train sensor status handling and sur- veillance. In such high-mobility scenarios, there are a number of communication challenges, including fast hand- over, location updating, high-speed channel modeling, estimation and equalization, anti-Doppler spreading tech- niques, fast power control, and dedicated network architec- ture. Because signal transmission in very high-speed scenarios will inevitably experience serious deterioration, it is imperative to develop key broadband mobile communi- cation techniques for such high-speed vehicles.     

Wuhan University Journal of Natural Sciences TOTAL CONTENTS

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海南岛地体及其毗邻陆缘晚中生代—新生代古地磁研究和构造演化

本文叙述了对海南岛及其毗邻大陆边缘白垩纪到第四纪地层岩石进行古地磁研究的全部工作过程。通过分析岩石中剩余磁矢量的磁偏角及磁倾角的变化,提出海南岛白垩纪以来经历的构造演化模式如下:早期伴随顺时针旋转而向南迁移,后期伴随逆时针转动并向北运移。联系该地区及邻区的地质、地球物理资料,对海南岛上述的构造地体运动提出以下认识:北部湾内早期有一拉张作用,主要是该作用使湾内地壳显著伸长减薄,形成北部湾盆地。从而导致了海南岛的早期构造运动,而海南岛后期的构造运动则主要是受南海海底扩张的影响。海南地体运动规律的阐明对于了解北部湾油气盆地的形成演化有重要的理论和实际意义。     

Scale-based spatial data model for GIS

Being the primary media of geographical information and the elementary objects manipulated, almost all of maps adopt the layer-based model to represent geographic information in the existent GIS. However, it is difficult to extend the map represented in layer-based model. Furthermore, in Web-Based GIS, It is slow to transmit the spatial data for map viewing. In this paper, for solving the questions above, we have proposed a new method for representing the spatial data. That is scale-based model. In this model we represent maps in three levels: scale-view, block, and spatial object, and organize the maps in a set of map layers, named Scale-View, which associates some given scales.Lastly, a prototype Web-Based GIS using the proposed spatial data representation is described briefly.     

Exciton Seebeck in Molecular Systems

Various applications relevant to the exciton dynamics,such as the organic solar cell,the large-area organic light-emitting diodes and the thermoelectricity,are operating under temperature gradient.The potential abnormal behavior of the exicton dynamics driven by the temperature difference may affect the efficiency and performance of the corresponding devices.In the above situations,the exciton dynamics under temperature difference is mixed with     

Achieving Unusual States of Matter Under High Pressure

The elongation method,originally proposed by Imamura was further developed for many years in our group.As a method towards O(N)with high efficiency and high accuracy for any dimensional systems.This treatment designed for one-dimensional(ID)polymers is now available for three-dimensional(3D)systems,but geometry optimization is now possible only for 1D-systems.As an approach toward post-Hartree-Fock,it was also extended to