课程文献中心 更多>>

关键词： 风荷载   环境振动   跨线天桥   动力响应   非一致激励  

摘要： 研究了环境振动对跨线天桥动力响应的影响。根据Reynolds时均化N-S的控制方程对列车风荷载湍流流场进行数值模拟,并结合车辆-轨道耦合动力学模型和轨道-枕木-大地三维有限元传递模型,获得了作用在天桥桥墩处的环境振动波。考虑到环境振动波传递的非一致特性,推导出非一致激励作用下跨线天桥的动力学方程。模拟出列车风和环境振动共同作用下跨线天桥的动力响应,对环境振动对跨线天桥动力响应的影响和跨线天桥的舒适度进行了分析。结果表明,在进行环境振动分析时,必须考虑其非一致激励特性,且环境振动对跨线天桥的振动响应有一定的影响。

关键词： 高铁站区位   距离指数   站点周边开发   设站城市规模  

摘要： 空间区位是影响高铁站周边地区开发的主要因素之一。以京沪高铁和武广高铁沿线38个站点为案例,探究高铁站到城市中心的距离对高铁站周边的开发规模、用地性质等方面的影响。研究发现,高铁站距离城市中心过近和过远均不利于站点周边地区的开发,且开发显著的样本以大城市及以上规模城市为主;就用地性质而言,道路用地占比最高,其次为居住和商务商业用地,表明站点周边仍处于建设开发初期;开发显著的站点与高铁交通功能密切相关的基本服务功能完善,而与城市价值相关的衍生功能差异较大。京沪线站点周边的开发规模远大于武广线,且商业类用地占比更高,这与两线路沿线城市规模和经济发展水平相关。

关键词： 一线员工   服务补救   知识获取  

摘要： 利用针对134位一线员工所做问卷调查的数据,建立了概念模型,采用偏最小二乘回归法(PLS)实证检验了一线员工的创新角色对其服务补救的影响。结果显示,一线员工的创新角色对服务补救的影响具有两面性:一方面,一线员工的创新角色不利于服务补救,因为获取消费者的信息耗时耗力;另一方面,创新角色有利于服务补救,因为获取消费者的信息能够激发一线员工的改进构想,对服务补救速度和质量产生积极影响。

关键词： 盾构地铁隧道   抗震设计   反应位移法   时程分析法  

摘要： 针对目前我国实行的《城市轨道交通结构抗震设计规范》,以西安地铁某号线为背景,基于盾构地铁区间隧道抗震设计方法—反应位移法与时程分析法的基本原理,对盾构地铁区间隧道进行了抗震分析。通过分析比较两种方法所得出的内力与关键节点水平位移,说明反应位移法和时程分析法在抗震设计中均具有适用性,两种分析方法可互相参考验证。

关键词： 共产党员   影响力   普通员工   党员的先进性   班组职工   党员示范岗   党员责任区   政治热情  

摘要： 发展一线班组员工入党,先要激发员工的政治热情和人党积极性,要让普通员工看到共产党员的先进性、优越性。要让共产党员在职工群众中树立起荣誉感、使命感,增强党员在班组职工中的影响力,带领班组职工一起搞建设,引领班组职工积极进步。走进中航工业长沙中传机械有限公司六分厂厂房,会看见这样一条鲜红夺目的横幅——＂一个党员一面旗帜＂,时刻感召着这里的每一位员工;在其他生产现场,＂党员责任区＂＂共产党员示范岗＂的标牌不经意间就闯入眼帘,

关键词： 社会迁移   永久性迁移人群   生育率  

摘要： 文章利用2008年中国综合社会调查的数据对长期迁移人口(户口随着人的迁移而变动的人群)的生育行为进行深入分析。基于3*3流动表格基础上分析人口流动的方向、距离和地域对生育率的影响,并通过将社会划分为农村阶层(农村和小镇)、准城市阶层(郊区和一般性城市)、城市阶层(包括省会、北京、天津和上海及其外围)来检测社会化假设、适应假设和选择性假设。结果显示人口迁移前后社会各阶层的生育率发生了改变,并且在方向和广度上发生了变化。短距离的向上迁徙可能增加生育率,而长距离的向下迁徙也可能显著地增加生育率,同时长距离的向上迁徙将生育率限制在了一定水平。相比原有阶层,在东西部地区迁徙的人对生育率产生了更大的影响;同时中部地区的原有阶层相比迁徙阶层对生育率产生了更大的影响。

关键词： Gravity centerline shift ratio   Lunar lander   Soft landing   Dynamics model  

摘要： In order to obtain the lunar lander soft landing performance impact caused by the body gravity centerline shift, a seven-degree-offreedom dynamic model is established based on the inertia force, and a dynamics and kinematics equation is deduced. The dynamic model was verified by the lunar lander scale model and soft landing impact experimental platform. Soft landing performance effects caused by the lander body gravity centerline shifts are analyzed according to the displacement of the body, the body overload, primary/ secondary pillar load, and buffer processes. The research results show that the gravity centerline shift has a significant influence on the lunar lander soft landing performance;when the lunar lander lands on the lunar slope-in a downward direction along the slope-the appropriate shift of the position of the gravity centerline can effectively improve the soft landing performance and stability. (C) 2014 American Society of Civil Engineers.

关键词： Weight function   Crack face displacement   Stress intensity factor   Center crack configuration  

摘要： The weight function method provides a powerful and reliable tool for the determination of the stress intensity factor around the crack tip in a linearly elastic cracked solid subjected to arbitrary loading conditions. However, it is difficult to exactly compute the crack face displacement whose partial derivative is responsible for the weight function calculation. In the present paper, only one reference stress intensity factor is used for the purpose of establishing a general expression of the crack face displacement. Then, the generalized and simple expression is applied to calculate the weight function and the stress intensity factor of the center crack configuration. The calculation of the weight function is reduced to the simple integration of the correction function and of the partial derivative of the crack face displacement. It is shown that the present expressions for the computations of the crack face displacement and its partial derivative are in good agreement with their exact solutions.

关键词： Helical rectangular channel   Torsion   Curvature   Frees surface   Velocity  

摘要： Helical channels have a wide range of applications in petroleum engineering, nuclear, heat exchanger, chemical, mineral and polymer industries. They are used in the separation processes for fluids of different densities. The centrifugal force, free surface and geometrical effects of the helical channel make the flow pattern more complicated;hence it is very difficult to perform physical experiment to predict channel performance. Computational Fluid Dynamics (CFD) can be suitable alternative for studying the flow pattern characteristics in helical channels. The different ranges of dimensional parameters, such as curvature and torsion, often cause various flow regimes in the helical channels. In this study, the effects of physical parameters such as curvature, torsion, Reynolds number, Froude number and Dean Number on the characteristics of the turbulent flow in helical rectangular channels have been investigated numerically, using a finite volume RANSE code Fluent of ANSYS workbench 10.1 UTM licensed. The physical parameters were reported for range of curvature (delta) of 0.16 to 0.51 and torsion (lambda) of 0.032 to 0.1. The numerical results of this study showed that the decrease in the channel curvature and the increase in the channel torsion numbers led to the increase of the flow velocity inside the channel and the change in the shape of water free surface at given Dean, Reynolds and Froude numbers.