A network optimization-based approach for crowd management in large public gatherings

Effective crowd management during large public gatherings is necessary to enable pedestrians' access to and from the venue and to ensure their safety. This paper proposes a network optimization-based methodology to support such efficient crowd movement during large events. Specifically, a bi-level integer program is presented that, at the upper-level, seeks a reconfiguration of the physical layout that will minimize total travel time incurred by system users (e.g. evacuees) given utility maximizing route decisions that are taken by individuals in response to physical offerings in terms of infrastructure at the lower-level. The lower-level formulation seeks a pure-strategy Nash equilibrium that respects collective behavior in crowds. A Multi-start Tabu Search with Sequential Quadratic Programming procedure is proposed for its solution. Numerical experiments on a hypothetical network were conducted to illustrate the proposed solution methodology and the insights it provides.     

Connecting e-hailing to mass transit platform: Analysis of relative spatial position

This paper analyzes and compares two different relative spatial position (RSP) designs in an integrated e-hailing/fixed-route transit system: a zone-based design that operates e-hailing vehicles within a zone, and a line-based design that operates e-hailing vehicles along a fixed-route transit line and with a stable headway. To conduct a meaningful comparison, the optimal design problems for both systems are formulated using a same analytical framework based on the continuous approximation approach. A comprehensive numerical experiment is performed to compare various cost components corresponding to the optimal designs, and a discrete-event simulation model is developed to validate the analysis. The analytical and simulation results agree with each other well, with a discrepancy in the total system cost less than 5% in most test scenarios. These results also suggest that the line-based system consistently outperforms the zone-based system in terms of both agency and user costs, for all scenarios tested. Compared to the zone-based design, the line-based design features a sparser fixed-route network (resulting in larger stop spacing) but a higher dispatching frequency. It is concluded that the higher efficiency of the line-based design is likely derived from the strategy of operating e-hailing vehicles with a more regular route/headway structure and allowing ride-sharing.     

材料参数对高速铁路连续梁桥地震易损性分析的影响研究

中等跨径的预应力混凝土连续梁广泛应用于高速铁路,以往震害及实验都表明该类桥型在地震下的破坏集中在桥墩和支座位置。为了研究材料参数对高速铁路连续梁桥地震易损性的影响,采用IDA方法,利用有限元软件Open Sees建立地震易损性分析模型。定义4种破坏极限状态,基于对数正太分布假设绘制各个破坏状态对应的易损性曲线。通过更改材料参数得到新的计算模型,并通过对比易损性计算结果来评价材料参数对桥梁抗震性能的影响。结果表明,高速铁路连续梁桥桥墩配箍率较低,提高桥墩混凝土强度等级对桥梁抗震性能改善较大。     

预应力混凝土箱粱桥裂缝成因分析

分析了预应力混凝土梁桥常见裂缝的产生原因,提出了设计中控制裂缝的方法,供工程技术人员参考。     

Error quantification of a high resolution coupled hydrodynamic-ecosystem coastal-ocean model: Part3, validation with Continuous Plankton Recorder data

Data collected during the Continuous Plankton Recorder (CPR) survey has been used to validate a three-dimensional hydrodynamic ecosystem model simulation of the North-west European Shelf for the years 1988–89. The CPR time series is unique to the North Atlantic region as a validation tool. Data were extracted from the model to correspond with those collected by the CPR survey, and both the model and survey plankton data were standardised to allow the comparison of model biomass with survey counts. Simple linear regression and absolute error maps provide a qualitative evaluation of spatio-temporal model performance of simulated diatoms, flagellates, total phytoplankton and omnivorous mesozooplankton. Comparisons of z-scores indicate that the model reproduces the main pelagic seasonal features, and there is good correlation between magnitudes of these features with respect to standard deviations from a long-term mean. The model is replicating up to 62% of the mesozooplankton seasonality across the domain, with variable results for the phytoplankton. There are, however, differences in the timing of patterns in plankton seasonality. The validation exercise has highlighted that the spring diatom bloom in the model is too early, suggesting the need to reparameterise the response of phytoplankton to changing light levels in the model. Errors in the north and west of the domain imply that model turbulence and vertical density structure need to be improved to more accurately capture plankton dynamics.     

连续刚构高墩施工托架预压技术

大河边特大桥主桥为预应力混凝土连续刚构桥，主墩上部结构箱梁1-0-1＇#块段采用预埋牛腿托架法施工方法，文章介绍该桥施工中采用的预应力施载的托架预压技术。     

浅谈箱梁混凝土质量通病治理措施

详细介绍了箱梁混凝土常见各种形式通病,提出了箱梁混凝土质量通病治理方案及实施保证措施。     

多跨高墩连续刚构的设计与探讨

以汝城至郴州高速公路文明特大桥（主桥为66＋6×120＋66=852 m的连续刚构）为例,探讨了多跨高墩连续刚构在结构方案比选、合拢工艺和下部结构优化等方面的问题。     

连续刚构桥沥青砼桥面铺装病害调查与分析

文章结合连续刚构桥梁自身的受力特点,通过定量分析桥面铺装的病害种类和分布情况,得出裂缝、变形与防水粘结层失效是其铺装层破坏的主要形式,并分析了病害产生的原因,提出以铺装层顶面的横向拉应力和底面剪应力为铺装结构分析的力学控制指标。     

大跨连续钢桁梁架设施工控制分析

向莆线东新赣江特大桥是一座（126＋196＋126）m下承式连续钢桁梁,全桥四线铁路共建,两片主桁,桥面系为整体正交异性钢桥面。在东新赣江特大桥连续钢桁梁拼装架设过程中,对其线形、应力和整体抗倾覆稳定性等方面进行施工过程控制,确保了钢梁架设施工过程中的结构安全和顺利精确合龙,使成桥的线形和内力达到了设计预期的理想状态。