Exploration of route choice behavior with advanced traveler information using neural network concepts

A model of driver's route choice behavior under advanced traveler information system (ATIS) is developed based on data collected from learning experiments using interactive computer simulation. The experiment subjected drivers to 32 simulated days in which they were to choose between the freeway or a side road. A neural network model is used as a convenient modeling technique in this initial phase of the analysis. The results indicated that most subjects made route choices based mainly on their recent experiences. It was also demonstrated that route choice behaviors are related to the personal characteristics as well as the characteristics of the respective routes. Travel experiences have less effect on the choice of the side road compared to the freeway and the results indicate that the prediction accuracy of the model, the acceptance rate of advice, and the quality of advice are closely correlated. The model developed here was for advice consistently provided at a level of 75 percent accuracy. The paper concludes with a discussion of experimental limitations and suggestions for future research.     

用逐步逼近弯曲求解型材弯曲弹复曲率的方法

本文从塑性弯曲理论推出了用逐步逼近弯曲求解型材弯曲弹复曲率的实用方法,对型材自动化弯曲成形工艺处理回弹问题十分有效。     

A cell-based Merchant-Nemhauser model for the system optimum dynamic traffic assignment problem

A cell-based variant of the Merchant-Nemhauser (M-N) model is proposed for the system optimum (SO) dynamic traffic assignment (DTA) problem. Once linearized and augmented with additional constraints to capture cross-cell interactions, the model becomes a linear program that embeds a relaxed cell transmission model (CTM) to propagate traffic. As a result, we show that CTM-type traffic dynamics can be derived from the original M-N model, when the exit-flow function is properly selected and discretized. The proposed cell-based M-N model has a simple constraint structure and cell network representation because all intersections and cells are treated uniformly. Path marginal costs are defined using a recursive formula that involves a subset of multipliers from the linear program. This definition is then employed to interpret the necessary condition, which is a dynamic extension of the Wardrop’s second principle. An algorithm is presented to solve the flow holding back problem that is known to exist in many discrete SO-DTA models. A numerical experiment is conducted to verify the proposed model and algorithm.     

后支点三角形分离式挂篮设计

后支点三角形分离式挂篮具有安全性能高、行走方便、自身结构轻、灵活多变等优点,能够成功解决斜拉桥主梁渐变段施工的难题,同时在施工标准节段和渐变节段时易于转换.以苏村坝大渡河大桥挂篮施工为例,介绍后支点三角形挂篮的设计,供类似桥梁设计参考.     

基于系统识别方法的隧道围岩参数反演分析

隧道围岩参数是判断隧道围岩及衬砌稳定性的重要手段,是隧道安全预警系统的重要组成部分.对于采用新奥法施工的隧道,通过对围岩收敛进行实时监控,并利用有限元软件ANSYS建立隧道开挖过程收敛变形的正演模型,得到了围岩收敛的数值解,在此基础上根据系统识别理论建立了隧道围岩参数反演分析方法,并结合工程实例反演得到了围岩参数.研究...     

基于配气正时的柴油机高排气背压性能优化

针对目前柴油机在高排气背压下泵气功损失增加、残余废气系数升高、燃油经济性下降等性能恶化的问题,提出通过优化配气正时来解决此类问题的方案。利用GT‐Power软件对LD1110单缸柴油机建立仿真计算模型,对上述解决方案进行了分析研究。计算结果表明：排气背压为0．3 M Pa、进气提前角保持不变、喷油量为45 mg时,柴油机在转速2200 r／min下通过优化排气晚关角可以使平均有效压力提高28．33％,有效燃油消耗率降低22．08％;排气背压由0．1 M Pa增大到0．3 M Pa时,通过配气正时优化,柴油机在转速2000 r／min下平均有效压力的损失可减小12．8％,有效燃油消耗率的增加可降低27．1％。     

顶进涵后背选型与设计

在顶进涵设计中,作为临时设施的后背设计是整个设计工作的重要环节之一。后背造价占整个工程投资的比重较大,后背设计是否合理,直接关系到整个工程的经济效益和施工工期。结合某顶进涵工程实例,介绍了后背结构形式的选择,根据现场情况重点阐述了重力式后背的结构形式、尺寸拟定及检算。实践证明,所选顶进涵后背结构经济合理,确保了施工和行车安全。     

利用摩擦系数反算法设定深水铺排船铺排系统滑板最佳倾斜角度

铺排船应用于航道整治工程中,滑板最佳倾角的设定是铺排船设计过程中一项重要的指标,很多工程施工通过经验确定,以排体缓缓下滑作为锁定滑板倾角的依据,特殊情况下无法准确判断该状态。"半潜1"船舶进行铺排改造后,通过多次现场试验验证得出滑板与联锁片的摩擦系数范围为0.348~0.380;设定边界条件后,利用摩擦系数反算法及反求技术得出滑板最佳倾角为27.83°~30.38°,在该范围内可实现甲板布置2 m,滑板布置单排联锁片顺利溜放,对滚筒拉力达到最佳。     

长江澄通河段下段采砂对航道及通航安全的影响

近年来,澄通河段采砂项目日益增多,河道采砂可能引起工程河段的局部河道调整、河床冲淤变化,给工程河段的航道与通航安全可能带来不利的影响。以福山水道南岸边滩整治工程为例,根据最新测图资料与水文测验数据,分析采砂后工程河段泥沙回淤情况,并讨论采砂对航道和通航安全的影响,对当地后续工程有参考意义。     

强夯法处治桥头台背路堤探讨

为处治桥头台背路堤,以避免桥头跳车现象的发生,应用夯击能的传递机理,采用强夯法加固台背路堤,桥头台背路堤质量得到大大提高。经过对多种方法的试验和评价,证明强夯法处治桥头台背路堤是目前为止相对较好的解决办法。