A pedestrian flow model considering the impact of local density: Voronoi diagram based heuristics approach

Local density, which is an indicator for comfortable moving of a pedestrian, is rarely considered in traditional force based and heuristics based pedestrian flow models. However, comfortable moving is surely a demand of pedestrian in normal situations. Recently, Voronoi diagram had been successfully adopted to obtain the local density of a pedestrian in empirical studies. In this paper, Voronoi diagram is introduced into the heuristics based pedestrian flow model. It provides not only local density but also other information for determining moving velocity and direction. Those information include personal space, safe distance, neighbors, and three elementary characteristics directions. Several typical scenarios are set up to verify the proposed model. The simulation results show that the velocity-density relations and capacities of bottleneck are consistent with the empirical data, and many self-organization phenomena, i.e., arching phenomenon and lane formation, are also reproduced. The pedestrians are likely to be homogeneously distributed when they are sensitive to local density, otherwise pedestrians are non-uniformly distributed and the stop-and-go waves are likely to be reproduced. Such results indicate that the Voronoi diagram is a promising tool in modeling pedestrian dynamics.     

我国运输企业财务治理探析

阐述了我国运输企业财务治理的现状,分析了运输企业财务治理中存在的问题,提出完善运输企业财务治理应该建立财务治理结构和目标机制、完善股权结构、合理配置财务治理权力、实行约束激励机制、强化外部监控和弱化政府干预、引入声誉机制建立经理人市场等对策。     

航海实践中"无害通过权"的运用

通过一个真实的案例对“无害通过权”的意义和运用加以分析,提醒航海人员灵活运用联合国海洋法条款中的无害通过权,以一个适当的视角看待海洋国际法。     

离散点集实时Delaunay三角网剖分算法的研究

为了解决分治算法、插入算法和生长算法都要求在构网之前给出所有点数据这个问题,实时三角网剖分算法先利用部分离散点生成一个外轮廓为凸包的初始三角网。然后将点加入到既有三角网中,如点落在既有三角网的某一三角形中,将该点与三角形的顶点相连构建新的三角网;如点落在既有三角网外,找出该点向既有三角网外轮廓围成的凸包发出的两条支撑线,这两条支撑线与既有凸包围成了一个多边形,再将这个多边形剖分成三角网即可。最后利用局部优化算法对所生成的三角网进行优化,使之成为Delaunay三角网。该算法构网时无需预先给定所有数据点,可用于实时生成三角网;此外,通过对凸包进行分区管理,在搜寻凸包支撑线时,能预先确定出支撑点的范围,减少了搜索工作量,提高了三角网的生成速度。     

闸次顺序对三峡船闸过闸效率的影响

三峡船闸为五级连续船闸,相邻闸次运行相互制约,在实际运行中不可避免出现相邻闸次"等闸"现象。为了进一步提高船闸的通行能力,基于大量运行数据,建立了五级上行船舶过闸仿真模型。通过模型仿真分析相邻闸次船舶数量与"等闸"的关系,研究闸次顺序对过闸效率的影响。仿真结果表明:前一闸次船舶数量大于后一闸次时,船舶数量差越小,"等闸"现象时间越短。通过优化闸次顺序,可有效缩短"等闸"现象时长,减小闸次间隔时间,从而提高日运行闸次。     

永鑫大桥墩梁塔固结部位应力分析

文章以永鑫大桥为研究对象,采用子模型计算方法对永鑫大桥墩梁塔固结部位进行有限元计算,分析了该部位的局部应力及横、竖向预应力设置对该区域的影响,其计算结果可为同类矮塔斜拉桥设计提供参考。     

小议政府海事信息公开——兼评《政府信息公开条例》对海事政务公开影响

现代法治国家发展历程表明，政务公开是是推进依法行政、建设法治政府的基本前提。政务公开同时是现代海事管理理念的体现，文章通过对相关制度及现状的研究，为海事机构适应新形势下政府信息公开工作提出了相应的建议。     

运政电子政务的地位与作用

介绍了运政电子政务的地位与作用,结合运营工作的实际,指出了运政电子政务对运营工作中技术应用的创新性。     

工程企业与政府合作开发项目的风险管理

研究目的:本文通过识别、评价与政府合作开发项目运作中的风险,提出工程企业风险规避的主要措施.研究结论:合作开发项目风险与一般工程项目风险不同,具有系统性、关联性、多样性等特点.风险管理应综合分析某类风险在总体风险系统中的重要程度及关联性.在与政府的合作开发项目中,要正确处理好政策变动风险、政府诚信风险、市场风险等风险因素,努力防范风险.     

Including local air pollution in airport efficiency assessment: A hyperbolic-stochastic approach

We examine data from Italian airports covering 2005–2008 to include local environmental effects in airport efficiency assessment. We consider both desirable outputs such as aircraft, passengers, and freight movements and some undesirable outputs of airport operations associated with local air pollution. We estimate both a classical distance function with no undesirable output, and a hyperbolic distance function. By comparing the estimated efficiency scores with these two frontiers we show that airport efficiency increases when local air pollution is included in the analysis. Moreover, we show a fleet-mix effect because airports with similar aircraft movements exhibit large variations in the amount of pollution per flight. Last, we find that there is complementarity between desirable and undesirable output: a 1% decrease in pollution has an opportunity cost of a 0.67% reduction in both passenger and freight traffic.