Micro-simulation modelling for traffic safety: A review and potential application to heterogeneous traffic environment

This paper critically reviews micro-simulation modelling applications for traffic safety evaluation with respect to the use of different simulation tools, the application of surrogate safety indicators under different aspects of road environments and crash considerations. General input variables used to develop the models; key parameters for crash prediction; and calibration and validation approaches are explored in the paper. The strengths and weaknesses of used simulation packages for traffic safety evaluation are also pointed out. Moreover, recent advancements in the development and application of traffic safety micro-simulation model for safety assessment are also discussed.Despite having a number of studies, there is still a significant void in the development and application of simulation model to evaluate traffic safety of non-lane based heterogeneous traffic environments that predominate in many developing countries. The paper assessed the potential application of traffic safety micro-simulation model in heterogeneous traffic environments. Finally, a number of potentially fruitful future research directions are highlighted.     

铁路隧道检测技术现状及发展趋势

传统隧道质量检测方法以人工检查为主,结果依赖于检测人员水平,效率极低,远不能满足现场需求。为了检测设备的研制和保障铁路隧道运营安全,通过调研国内外多种隧道检测新技术和不同类型的综合检测车,分析现有隧道检测技术的特点,结果表明:目前的检测技术存在病害检测指标相对单一、自动识别程度低、检测速度较慢等问题。提出铁路隧道检测环境与公路隧道及城市轨道交通相比存在的一些差别,得出铁路隧道检测技术有以下发展趋势:(1)隧道衬砌质量无接触式检测;(2)激光扫描将成为表面病害主要检测方式;(3)检测设备高度集成化;(4)检测数据采集和处理自动化;(5)铁路隧道检测车需采用专用轨道车辆。     

Logistics as a driving force for development under the Belt and Road Initiative – the Chinese model for developing countries

ABSTRACT

An important objective of “the Belt and Road Initiative” is to promote the economic growth of countries in the region. China’s successful development experience, proposed in the initial stage of reform, can be summarised as “Looking for development, building the highway first”. This study is the first to evaluate whether logistics infrastructure has indeed contributed to economic growth by employing an error correction model with panel data from 2003 to 2014. In addition, we compare the influence levels of different sectors of logistics infrastructure in different regions, i.e. developed and developing regions. We focus on developing regions as they represent good development experiences for developing countries in the Silk Road Economic Belt. For developing regions, we find that the most influential factors are telecommunication and airway transportation, which should be the foci of attention in order to promote economic growth and reduce inter-region economic inequalities. The research confirms that logistics is indeed a driving force for economic growth in China, and that the contributions of specific sectors can be a useful reference for developing countries to determine prioritisation of investment in different logistics sectors across regions.     

船用厚板高强度钢焊接性及其焊接裂纹的形成和预防

随着各类大型化、超大型化船舶的诞生,使得厚板高强度钢的使用日益广泛,但随之而来的是此类高强度钢易产生焊接裂纹的问题。文章列举了国内外船用厚板高强度钢焊接的工艺特点,分析了焊接裂纹的起因,并就预防措施进行了初步探讨。对从事船体结构的研究人员有一定的帮助。     

防城港市中越国际道路旅客运输发展探析

文章介绍了防城港市中越国际道路旅客运输的现状,分析了限制中越国际道路旅客运输发展的原因,阐述了防城港市发展国际道路旅客运输的重要性、有利条件和机遇,并提出了中越国际道路运输的发展思路。     

Importance of user perception in evaluating level of service for bus transit for a developing country like India: a review

Assessment of service quality in bus transit planning has received due attention in recent years from the viewpoint of optimal service allocation. The concept of level of service (LOS) has emerged as an effective tool to measure quality of services. Service-quality assessment provides operators with knowledge on users' satisfaction with existing services and their expected LOSs. The importance of user perception towards assessment of LOS has been acknowledged by researchers. While LOS standards for public transportation have been established by the Transportation Research Board in the USA, researchers have questioned the applicability of these standards in the context of different geographic regions. Since the service delivery environment differs between developed and developing nations, the user perception of service quality varies between these economic regions. Substantial research has been carried out in the context of both developed and developing nations, to identify the bus transit service parameters that affect users' perceived service quality; however, little research exists that establishes LOS thresholds for bus transit, based on user perception. This paper reviews the concept of LOS, describes the importance of user perception in assessment of service quality and identifies the need to establish LOS thresholds for bus transit from user perception for developing countries.     

Lateral dynamics of motorcycles towing single-wheeled trailers

A motorcycle towing a single-wheel trailer may provide useful transport for light cargo on narrow tracks and off-road use, particularly in rural areas of developing countries. Four designs of such trailers are described. Linear models are derived for the lateral dynamics of an off-road motorcycle towing this type of trailer straight ahead at constant speed. The trailers were tested behind an instrumented motorcycle. Linear autoregressive models were fitted to the experimental data using system identification techniques. Analytical and experimentally derived models largely agreed on frequency, damping and shape of the weave, wobble and trailer sway normal modes. The trailers made the motorcycle's steering heavier but the analytical models did not predict this. The location of the articulation axes between the motorcycle and the trailer were found to be critical for stability. The best trailer design handled well with loads up to 200 kg and speeds up to 70 km/h.     

21世纪的汽车发动机

从降低排放，改善燃油经济性两个方面，论述了２１世纪车用汽油机和车用柴油的发展趋势，经分析指标出，两种发动机在改善性能，降低排谚方面可以取长补短，相互相借鉴其新技术。