浅谈商用车门框胶条密封性的改进方案

本文通过对商用车门框胶条漏水原因的分析,简要介绍如何从门框胶条的结构设计进行改善,进而改善商用车胶条的密封性能,为解决商用车门框胶条漏水问题提供理论支持。     

Meta-frontier function approach to operational efficiency for shipping companies

ABSTRACT

This study uses a meta-frontier function approach to estimate operational efficiency and technology gaps for shipping companies. Researchers have evaluated the relative efficiency of shipping firms with the assumption that shipping firms operate under one frontier technology. However, the assumption of one frontier technology is being argued by efficiency literature. Therefore, this study estimates relative efficiency of shipping firms in different market segments (dry bulk, liquid bulk, and containerized cargo), possibly operating with different technologies and, hence, under different frontiers. This study uses a meta-frontier function approach that allows us to distinguish separate frontiers for different groups and decompose efficiency scores relative to the meta-frontier. Data used in this study is collected from Thomson One Banker from 2001-2013 in the form of unbalanced panel data. Empirical results suggest that dry bulk firms’ production technology is more advanced than others and the production frontier is the closest to that of the meta-frontier. In addition, efficiency scores are all low, but containerized cargo firms achieve higher technological efficiency than the other two groups. It is also suggested that containerized cargo and liquid bulk firms should prioritize improvements in their production technology and dry bulk firms should prioritize improving group efficiency.     

成都地铁1号线地铁车辆塞拉门常见故障及处理方法

结合塞拉门机械机构和工作原理,主要介绍了成都地铁1号线地铁车辆塞拉门常见故障及改进处理方法,为以后相似类型的塞拉门系统故障提供处理经验。     

Improvements for the stability of heavy-haul couplers with arc surface contact

To investigate the stability mechanism of heavy-haul couplers with arc surface contact, the geometry and force analysis were conducted according to the friction circle theory. To improve the stability of the coupler, four improvements were proposed, which are increasing the secondary lateral stiffness of locomotives, adding a restoring bumpstop at the end of the coupler, increasing the arc surfaces radii and changing the clearance and stiffness of secondary lateral stopping block. A multi-body dynamics model with four heavy-haul locomotives and three detailed couplers were established to simulate the emergency braking. In addition, the coupler yaw instability was tested to investigate the effects of relevant parameters on the coupler stability. The results show that increasing the secondary lateral stiffness of locomotives, adding a bumpstop with a smaller bumpstop gap, increasing the arc surfaces radii, increasing the stiffness and decreasing the clearance of secondary lateral stopping block are conducive to improving the stability of the coupler with arc surface contact.     

Distribution of vehicle operating costs/benefits to a rural population

Assessment of economic benefits resulting from the provision of transportation projects are standard practice. However, the procedures seldom consider detailed distribution of benefits amongst the study area population. Distribution of vehicle operating cost benefits to rural population is presented for a road sealing project.     

Deciding whether and how to improve statewide travel demand models based on transportation planning application needs

Many states in the USA have developed statewide travel demand models for transportation planning at the state level and along intercity corridors. Travel demand models at mega-region and provincial levels are also widely used in Europe and Asia. With modern transportation planning applications requiring enhanced model capabilities, many states are considering improving their four-step statewide demand models. This paper synthesizes representative statewide models developed with traditional four-step, advanced four-step, and integrated micro-simulation methods. The focus of this synthesis study is as much on model applications and data requirements as on modeling methods. An incremental model improvement approach toward advanced statewide models is recommended. Review findings also suggest model improvement activities should be justified by planning application needs. For statewide model improvement plans to be successful and financially sustainable, the return on model improvement investment needs to be demonstrated by timely applications that rely on improved model capabilities.     

建设项目全寿命周期一体化管理模式探讨

文章针对传统项目管理模式的弊端,结合当前建设项目发展的趋势,从项目全寿命周期的角度出发,对建设项目全寿命周期一体化管理模式进行了初步探讨。同时分析了此模式下的项目运作流程、组织实施和信息一体化平台,旨在通过寻求一种合理有效的管理模式,适应建筑项目发展的现实需要,也为同类项目问题的解决提供参考。     

数据库体系化环境及若干问题研究

数据库体系化环境能够完整、细致地反映企业中的数据组织与处理.本文结合实际应用案例,提出了建立企业数据库体系化环境的实施策略,并讨论了相关问题的处理.     

基于模糊贝叶斯网络的山区高速铁路桥梁运营风险评估

针对山区高速铁路桥梁风险情况复杂且影响巨大的特点,提出基于模糊贝叶斯网络,建立山区高速铁路桥梁运营风险评估模型。将山区高速铁路桥梁风险损失划分成3类,分别列出各类损失的风险因素,构建桥梁运营风险概率评估的贝叶斯网络,通过专家调查法统计出桥梁风险因素的概率等级分布,并根据链式传递规则计算出风险事故的概率等级分布。然后,结合风险矩阵对桥梁运营风险水平进行评估。最后,利用该方法分析贵广高速铁路上云阳双线特大桥的运营风险。结果表明,建立的模型计算过程简便,评价结果符合实际,具有较高的实用性。     

浅谈运营高速公路边坡石方爆破施工方法

运营高速公路上边坡石方爆破是工程建设领域的一个难题,常规爆破必然危及高速公路自身结构安全和行车安全。文章介绍了石方普通爆破、孔外延时孔间微差定向松动爆破、劈裂机静态爆破三种不同的爆破方式,并针对运营高速公路实际,提出结合运用孔外延迟孔间微差定向松动爆破和劈裂机静态爆破两种爆破方法,能有效地对运营中的高速公路上边坡石方进行安全爆破。