浅谈轮式装载机转向系统

轮式装载机转向系统的功用是操纵车辆的行驶方向,系统应能根据需要保持车辆稳定地沿直线行驶,并能根据要求灵活地改变行驶方向。对转向系统的基本要求是操纵轻便灵活,工作稳定可靠,使用经济耐久。转向性能是保证车辆安全行驶,减轻驾驶员的劳动强度,提高作业生产率的重要因素,也是决定轮式装载机安全性和作业效率的关键环节。如何设计轮式装载机的转向特性,使装载机具有良好的操作性能和较高的作业效率,始终是生产厂家和科研机构关注的重要课题。     

JYL210E型轮胎式液压挖掘机

介绍JYL210E型液压挖掘机在JYL161-3型基础上重新设计的主要内容,在工作装置、推土铲和车架结构上作了改进,增加了悬挂油路系统,配备了机电一体化数字式仪表显示器,整机质量有较大提高,增强了产品的市场竞争力。     

液力机械传动变速器测试台的开发实践与经验

液力机械传动变速器总成是轮式装载机上的关键部件。该部件制造装配完成后,出厂或进行整机装配前必须对产品总成进行检测。介绍了一种装载机液力机械传动变速器总成检测试验台的设计思路与具体方案。该测试台技术先进,可满足批量生产的产品检测要求。经实际使用,效果良好,并在调试和应用中取得了一些经验。     

“Mapping” Smart Cities

ABSTRACT

Smart cities are designed to use data to optimize resources, maintain sustainability, and improve people’s quality of life. While many urban technologies are employed to make cities “smart,” one constellation of technologies has been less examined in the academic literature—digital maps and the spatial data infrastructure. This paper is an attempt to systematically review the functions and evolution of digital maps and the spatial data infrastructure, with examples from Asia and beyond, in supporting and making smart cities possible. Based on the conceptual framework and empirical case studies, four major research directions of smart mapping are identified to better support smart city initiatives.     

LES study of the influence of the nose shape and yaw angles on flow structures around trains

Large-eddy simulation (LES) is made of the flow around a generic train model at two different yaw angles of 90^° and 35^°. The Reynolds numbers, based on the freestream velocity and the height of the train, are 3×10⁵ and 3.7×10⁵ for the yaw angles of 90^° and 35^°, respectively. The primary objective is to investigate the influence of the nose shape and yaw angles on the flow structures and the train aerodynamics. Both the time-averaged and instantaneous flows are explored. In the case of the 90^° yaw angle, the LES results show that the influence of the three-dimensional flow from the nose of the train on the time-averaged wake flow is limited to a region of a length of 3.5 train heights from the tip of the nose in the direction of the length of the train. The instantaneous flow shows an unsteady vortex shedding due to the shear layer instabilities on the periphery of the recirculation region and the exterior flow. In the case of the 35^° yaw angle, weak vortex shedding is found in the wake. Instead, unstable vortices are found in the lower part of the recirculation region. These vortices detach from and reattach to the train surface in a regular fashion leaving disturbances on the train surface and hence affecting the aerodynamic coefficients. The influence of the shape of the nose on the flow structures is investigated by repeating the simulations at the 90^° yaw angle on a short nose model. The short nose model is identical to the long nose model whilst the length of its nose is half that of the long nose. The short-nose simulation shows highly unsteady and three-dimensional flow around the nose yielding more vortex structures in the wake. These structures result in a surface flow that differs from that in the long-nose train flow. They also influence the dominating frequencies that arise due to the shear layer instabilities.     

福州火车站站前地下广场建筑设计

本文通过福州火车站站前地下广场工程建筑设计实践,论述了在地下空间建设复杂的交通枢纽及综合商业建筑工程的可能性和现实意义。     

高速开关阀控制的高速列车横向半主动减振器

能根据列车运行状况实现阻尼特性的调整是列车横向半主动减振器的基本要求。利用高速开关阀可使减振器实现阻尼特性的在线调整。本文介绍了两种形式的基于高速开关阀控制的半主动减振器工作原理。     

轿车轮毂轴承毛坯塔锻工艺

介绍了轿车轮毂轴承毛坯的塔锻工艺设计及其模具设计。     

过程自动化实习培训装置的设计制造

介绍了一种实习培训装置，该装置新型、实用，具有强大的功能，能开出全部自动化单元及系统实验，DDC控制和SPC控制的实验。具有优良的性能价格比。     

基于着色Petri网的无线闭塞中心安全加密

针对中国列车控制系统（CTCS）-3级列车控制系统中的车地安全通信问题,采用层次化建模思想,设计了一种基于Petri网理论的无线闭塞中心（RBC）和列车之间信息交互的模型,并应用着色Petri网（CPN）tools仿真工具动态仿真了列车和RBC之间传输信息的生成、加密和发送的整个过程。该模型主要分为三个部分：列车申请行车许可（MA）、RBC生成完全监控模式下的MA和列车通过无线网络接收到MA并按照MA进行安全控车。运用动态仿真和状态空间分析工具对所提模型进行仿真分析可得,所设计模型能够满足车地信息传输的设计需求规范,具有有界性、活性、回归性和公平性,可用于车地信息的安全传输,减少软件设计缺陷。