Analysis of a Passive Sequential Hydraulic Damper for Vehicle Suspension

Vibration isolation characteristics of a sequential hydraulic damper, employing external pressure relief valves, are investigated via analytical means. The sequential hydraulic damper is modelled as a nonlinear dynamical system incorporating nonlinearities due to orifice flows, gas spring and pressure relief mechanisms. The damping characteristics of the sequential hydraulic damper, are compared to those of a constant orifice and a semi-active sequential damper, and discussed in view of their vibration isolation performance. It is established that the performance characteristics of the sequential hydraulic damper are similar to that of a semi-active sequential damper. A tuning methodology to achieve appropriate control of the resonant peak and effective vibration isolation is proposed. The shock and vibration isolation performance of the vehicle model employing a sequential damper are evaluated and compared to those of the vehicle model employing a constant orifice hydraulic damper. It is concluded that the vehicle ride performance can be improved considerably using an adequately tuned sequential damper.     

铁路新型快餐饭盒降解性能及评价方法的研究

在国内首次对新型快餐饭盒的光、生物降解性能及评价方法进行了比较全面、系统、深入的研究。第一次提出以光辐射累积能量（自然光源为３００ＭＪ／ｍ２，氙灯光源为１６．８００ＭＪ／ｍ２）取代目前以时间（ｈ、ｄ）为光降解试验控制参数，及以重均分子量下降率（７０％）作为光降解性能的定量评价参数。从而改善了原试验结果准确性、可比性、重现性差的不足；明显缩短了试验周期，降低了成本。还证实光降解到一定阶段时可加速生物降解的进程。     

铁路新型快餐盒产品质量分析

为保证入路供货的新型快餐盒的产品质量，铁道部安全卫生检验站对３种新型快餐盒进行了安全卫生、使用性能及环保性能检验，通过对检验数据的统计分析，提出了３种新型快餐盒的现状及存在问题。     

Track Induced Heave-Pitch Dynamics of Vehicles with Variable Section Flexible Attachments

Multi-wheeled vehicles travelling on a rough track are subjected to unequal inputs at different wheel locations and are set to oscillate in various combinations of possible modes. Elastic bending and torsional deformations may be critical in design for vehicles with slender flexible body and components. In the present study, an analytical approach has been developed to study the track induced heave-pitch dynamics of a linear vehicle model composed of lumped masses and slender, non uniform section elastic attachments in coupled bending-torsion modes. Exact modal solutions for the variable section beam member with general end conditions have been derived and utilised to develop the second order response statistics for the system. Results are presented for an aircraft model with tapered flexible wings during ground runs on a non homogeneously profiled track supported by elastic foundation.     

LY-I型语音记录装置的设计与实现

叙述了LY－I型语音装置的原理、特点和软件流程。应用DSP技术对语音信号进行处理、压缩和记录，以实现对车机联控语音和列车当时状态信息的记录，从而规范乘务员的工作用语和协同监控装置分析行车事故。该产品通过试验和现场运用，证明完全符合设计要求。     

南京地铁暗挖隧道防水设计与施工技术

本文结合工程实际，就南京地铁暗挖隧道防水设计与施工技术进行了探讨，为今后类似工程提供参考。     

IMO人的因素、培训和值班分委会第1次会议(HTW1)召开

正IMO人的因素、培训和值班分委会第1次会议(以下简称HTW1)于2014年2月17—21日在英国伦敦召开。本次会议对于与保安相关证书效力问题进行进一步明确。根据STCW公约马尼拉修正案,海员持有的与保安相关的证书分三级,依次是保安意识培训合格证(我国证书编码B07)、负有指定保安责任船员培训合格证(我国证书编码B08)和船舶保安员培训合格证(我国证书编码B09)。关于三级证书的相互之间的关系问题,HTW1明确了"高盖低"的原则,即持有了高一级的证书,就无需持有     

Can bus really be the new tram?

BRT appears to be less expensive to build and operate than tram systems but can it really approach the performance level of a tram system and what is the environmental performance of comparable systems?     

Multi-period Research Designs for Identifying Causal Effects of Built Environment Characteristics on Travel Behaviour

Abstract

To date, most empirical studies have applied cross-sectional designs to investigate the relationship between the built environment (BE) and travel behaviour (TB). Since these studies cannot identify causal influence, the use of designs that provide data on multiple moments in time seems necessary. This article classifies these designs and describes how they can be applied to identify causality in this relationship. We recommend the use of natural experiments to assess the impact of changes in land use/infrastructure and prospective longitudinal designs to assess the impact of residential or job moves. In addition, the role of the BE can be explored by assessing the impact of (1) deliberate TB change experiments and (2) changes in household circumstances across different spatial contexts over time. The use of randomised experimental designs is recommended for the former and prospective longitudinal designs for the latter. The article concludes with an outlook on future research.