Methodological Options and Data Sources for the Development of Long-Distance Passenger Travel Demand Models: A Comprehensive Review

Since the passage of the Intermodal Surface Transportation Efficiency Act in 1991, a significant number of state highway agencies have started to develop and implement statewide travel demand models to meet policy and legislative development needs. Currently, however, a lack of up-to-date multimodal and inter-regional passenger travel data hampers analysts’ ability to conduct quantitative assessments of long-distance travel infrastructure investment needs, at both the national and statewide levels. Despite these data limitations, but also largely shaped by them, long-distance travel modelling has become an increasingly popular topic in recent years. This paper reviews several methodologies for multimodal inter-regional travel demand estimation, drawing examples from both state-specific modelling within the USA and from fully national models being developed and applied in other parts of the world, notably in Europe.     

码头结构受重载冲击的数值仿真研究

近年来我国港口码头泊位超负荷运行的情况渐多,随着码头泊位靠泊能力的升级,码头结构遭受破损荷载冲击的可能性在加大。结合某港口码头抓斗碰撞事故的实例,采用ANSY/LS-DYAN有限元分析软件对该事故进行数值仿真计算,分析码头横梁的破损原因和整个碰撞过程的能量转换,通过编程后处理研究码头横梁的受力状态及规律。     

土的压缩模量随荷载的变化规律分析

目前,土的压缩模量被认为是一个近似常数的做法是不合理的。结合港珠澳大桥工程室内压缩试验成果,分析不同应力区间和不同应力路径下土的压缩模量变化规律,并分析不同条件下的压缩模量变化幅度,为土的变形计算参数取值提供参考。     

CFD simulation of fixed and variable pitch vertical axis tidal turbine

In this paper, hydrodynamic analysis of vertical axis tidal turbine (both fixed pitch & variable pitch) is numerically analyzed. Two-dimensional numerical modeling & simulation of the unsteady flow through the blades of the turbine is performed using ANSYS CFX, hereafter CFX, which is based on a Reynolds-Averaged Navier-Stokes (RANS) model. A transient simulation is done for fixed pitch and variable pitch vertical axis tidal turbine using a Shear Stress Transport turbulence (SST) scheme. Main hydrodynamic parameters like torque T, combined moment C _M , coefficients of performance C _P and coefficient of torque C _T , etc. are investigated. The modeling and meshing of turbine rotor is performed in ICEM-CFD. Moreover, the difference in meshing schemes between fixed pitch and variable pitch is also mentioned. Mesh motion option is employed for variable pitch turbine. This article is one part of the ongoing research on turbine design and developments. The numerical simulation results are validated with well reputed analytical results performed by Edinburgh Design Ltd. The article concludes with a parametric study of turbine performance, comparison between fixed and variable pitch operation for a four-bladed turbine. It is found that for variable pitch we get maximum C _P and peak power at smaller revolution per minute N and tip sped ratio λ.     

基于AD2S1210的EPS电动机转子位置检测研究

设计了一种EPS助力电动机转子位置的检测方法,该方法采用旋转变压器作为传感器,使用新型的RDC芯片AD2S1210将旋转变压器的输出信号进行解码,并设计了外围电路与电流增益驱动电路,对数据的读取方法进行了介绍。实验表明,该系统工作性能良好,符合EPS助力电动机的转子位置检测要求。     

易密实沥青混凝土薄层罩面技术在养护维修工程中的应用

该文对易密实沥青混凝土薄层罩面技术的应用作了论述。易密实沥青混凝土ECA-10摊铺厚度为2.5 cm,使用易密实添加剂,保证了薄层沥青混凝土的压实度。其特有的级配满足了细粒式沥青混凝土作为表面层的抗滑要求。2.5 cm的易密实沥青混凝土薄层罩面技术作为高速公路的预防性养护措施,其性能优良、造价经济,值得推广应用。     

地震作用下多跨简支梁桥挡块优化设计研究

为研究墩柱损伤时弹塑性挡块的合理参数设计,以三跨简支梁桥为例,建立了OpenSees有限元软件计算模型.通过非线性时程分析,动态调整挡块屈服强度,建立了挡块屈服与墩柱损伤状态之间的直观联系,分析了弹塑性挡块初始刚度、屈服后刚度比参数.研究结果表明:挡块强度的增大,其限位能力也增强;当桥墩挡块强度的设定以桥墩达到中等损伤为目标时,有利于地震惯性力合理分配;挡块初始刚度的增大,可有效降低主梁位移响应,其对桥墩地震响应的影响较挡块强度的小;强震作用下挡块屈服后,桥梁地震响应对挡块屈服后刚度的变化十分敏感,较小的屈服后刚度比对下部结构抗震有利,同时不会造成上部结构位移需求的急剧增长.     

五菱宏光S车型尾门锁系统的改进建议

介绍五菱宏光S车型的中控门锁系统中新增的尾门锁控制的功能和特点;结合中控门锁电路图,分析其工作方式;指出该系统存在的不足并提出改进建议。     

基于Workbench变速器齿轮轴的疲劳分析

使用Catia软件对齿轮轴进行实体模型,通过Workbench软件的高效率模型导入功能实现了Catia和Workbench的联合仿真,对齿轮轴进行静力学分析,结果表明设计的齿轮轴能满足强度要求。获取了循环载荷谱和材料的S-N曲线,对齿轮轴进行疲劳分析,得到了齿轮轴的寿命、损伤及安全系数等相关参数。结果表明齿轮轴的疲劳寿命能满足设计要求,为齿轮轴的结构设计及优化提供一定的参考依据。     

医院污水挥发性酚污染问题的防治对策的探讨

报道了广州市医疗部门所排污水中造成污染主因的挥发性酚的污染状况同时对次氯酸钠(NaOCl)代替酚制剂的消毒效果及污水中挥发性酚浓度变化进行了探讨。结果表明,NaOCl不但消毒效果优于经典的含酚型消毒剂,并且减少酚污染和经济效益等方面都有较好的效果。