基于图论的城市轨道交通网络连通性研究

根据图论基本概念,结合城市轨道交通网络运营特点,通过构建矩阵并计算特征根,研究其代数连通度的变化规律,提出基于图论的城市轨道交通网络连通能力的诠释与量化方法。该方法从网络全局的高度分析网络性能,计算过程简便易行,具有实际应用价值。     

Developing Transport Infrastructure in Sub-Saharan Africa through Public–Private Partnerships: Policy Practice and Implications

In contemporary times, Public–Private Partnership (PPP) in transport infrastructure has gained considerable attention in developing regions following its success in the developed countries. However, Sub-Saharan Africa (SSA) is among the developing regions with few transport PPP projects and among the regions with high number of failed projects. Meanwhile the region's transport infrastructure need far exceeds it current provision. This paper therefore aims to examine the project experiences (success and failure factors) of three highly profiled transport PPP projects, namely the Lekki toll road concession project (Nigeria), N4 toll road (South Africa/Mozambique) and Port of Maputo (Mozambique) in order to develop policy measures for effective future implementation. The experiences of the three projects show that transport PPP policy is indeed feasible in SSA. However, to realise its full applicability, proper policy actions and measures must be carefully observed and these include effective and efficient stakeholder management, transparent and competitive tendering process, high participation of local investors, stable macro-economic conditions and strong government commitment and regulatory framework. The projects experiences and policy actions developed are impactful in accelerating transport infrastructure development through PPP approach in SSA. Hence it is hoped that policy-makers and practitioners would be informed on the key strategies to employ in implementing future projects.     

秦沈客运专线路基基床表层级配碎石施工技术

结合秦沈客运专线路基技术工艺标准,从现场施工的角度对路基基床表层级配碎石的施工工艺进行了总结,并就路基基床表层级配碎石的施工方法和有关问题进行了初步探讨.     

城市轨道交通客流特征分析在可研阶段的应用

城市轨道交通的工程可行性研究是一项涉及众多专业、复杂程度高、综合性强的系统工程,为更准确地把握客流特征,根据城市轨道交通工程可行性研究阶段客流预测的主要内容,就反映沿线区域特性的客流预测指标进行分析,包括高峰小时客流量、平均运距、换乘系数、区域OD和客流不均衡性等,以长春北湖线一期和成都10号线一期工程可行性研究为例,从与上位规划的符合性、线路特点的一致性和对工程方案的指导性3个方面阐述多指标结合的客流特征分析方法。     

Experimental modeling of controlled suspension vehicles from onboard sensors

In this article, identification of vertical dynamics of vehicles with controlled suspensions is considered. Identification is performed from experimental data measured on a four-poster bench test of a segment C car, equipped with a CDC-Skyhook dampers control system. The measurements are obtained from the onboard accelerometers needed by the control system. A nonlinear model in regression form is identified, having the road profile and damper control currents as inputs and chassis accelerations as outputs. The model is identified by means of a set membership structured identification method, which takes advantage of physical information on the structure of the system, decomposing the system into three subsystems: one represents the chassis and engine and the other two represent the overall behavior of front and rear suspensions, wheels and tires. This decomposition allows us to avoid the complexity accuracy problems derived from the high dimension of required regression space. Indeed, the overall high-dimensional identification problem is reduced to the identification of lower dimensional subsystems and to the estimation of their interactions. An iterative scheme is used for solving the decomposed identification problem. As the chassis pitch is small for the usual road profiles, the chassis-engine block is considered linear and standard linear methods are used for its identification. The other two subsystems are the main sources of nonlinearities in the system, mainly due to the significant nonlinearities of controlled dampers and of tires. Owing to the complexity/accuracy problems of a physical modeling of these subsystems, an input–output approach is taken. In particular, a nonlinear set membership method that does not require the search of the functional form of involved nonlinearities is used for the identification of these subsystems. The iterative algorithm converged in two iterations to a model providing a quite satisfactory simulation accuracy for all the considered road profiles and CDC-Skyhook settings.     

广州南站施工组织难点及对策措施

针对广州南站项目施工组织的特点及重难点,阐明了大型综合工程项目三通一平的重要性,水平和垂直运输应采取多种措施协调配合,在加强现场管理的前提下,要加大设备的投入,并重点介绍了吊模及纵横向行走式施工模架等施工方案。     

鄂东长江公路大桥索塔锚固区节段模型试验研究

以鄂东长江公路大桥索塔锚固区为研究对象,采用1:1足尺模型试验与有限元分析相结合的方法,研究钢锚箱与混凝土组合结构索塔在不同索力状态下的受力特性和混凝土的抗裂性能,模型试验最大荷载为1.6倍设计组合索力.研究结果表明:试验荷栽为1.0倍设计组合索力时,塔壁裂缝位于边跨侧索导管口上方,最大宽度为0.15 mm,小于设计允许裂缝宽度,钢锚箱上测点最大应力为94.6 MPa,个别部位存在应力集中现象,但钢结构整体处于结构弹性范围内;试验荷载为1.6倍设计组合索力时,塔壁最大裂缝宽度扩展至O.27mm,组合结构能继续承载,说明结构有足够的安全度.     

温度对玻璃纤维土工格栅力学性能的影响及不确定度评定

为研究路面热铺沥青对玻璃纤维土工格栅力学性能的影响,选取了3种规格的玻璃纤维土工格栅,对不同温度作用的玻璃纤维格栅试样,就温度对其拉伸断裂强力和断裂伸长率2项力学性能的影响进行了大量的试验研究：并运用统计学中的柯尔莫哥洛夫检验法和格拉布斯准则对试验结果进行了分析及异常值剔除,得到其温度与拉伸力学性能关系曲线;在此基础上,运用标准不确定B类评定办法对试验结果进行了评定。分析研究表明,经不同温度作用后,玻纤格栅断裂强力和断裂伸长率无明显变化;力学性能与温度之间未呈现出明显的统计规律性.     

民用机场乘客登机流程优化综述

基于近年来民用机场乘客登机流程优化研究,从面向乘客、面向飞机、面向研究方法和面向新冠肺炎疫情方面分析了当前研究现状和研究成果,探讨了民用机场乘客登机流程优化的方法及措施,根据现有研究的不足展望了未来的研究方向。研究结果表明：面向乘客的优化研究通常将群体乘客作为主要考虑因素,以最小登机时间及登机干扰作为目标函数建立相关模型,并针对不同优先级乘客和迟到乘客进行分组考虑;WilMA和RP是综合性能较优的2种登机策略,Side-Slip新型座椅对登机时间影响最显著;乘客登机优化的求解方法包括模型法和仿真法,其中模型主要包括统计物理模型和数学模型,仿真包括元胞自动机和智能体;面向新冠肺炎疫情的登机研究更多地考虑了乘客的健康问题,并将登机时间和健康风险作为评估登机优劣的两大主要指标;未来研究需综合不同登机策略的优点以弥补单个策略的不足;自主性强的智能体仿真和未突出个体性差异的元胞自动机仿真需要相互结合;优化模型应考虑更多因素,寻找求解质量更高的启发式算法;需更加注重社交距离、戴口罩乘客人数及群体登机人数等对疫情环境下登机流程的影响研究;疫情防控常态化情况下如何最大化乘客安全和登机效率也是重要的研究方向。     

掺硅灰对中等强度混凝土力学性能影响的试验研究

硅灰作为一种活性粉末,掺入混凝土中能有效地提高混凝土的抗压强度、弯拉强度、耐磨性和抗渗性等．因而被大量应用于高强、高性能混凝土的研制中。通过试验研究硅灰不同掺量对中等强度混凝土力学性能——抗压强度、抗折强度、劈裂强度、应力应变和弹性模量等的影响,初步得到中等强度混凝土中硅灰的合理掺量,有助于提升硅灰在路面混凝土中的应用价值和前景．