Finite Disturbance Directional Stability of Vehicles with Human Pilot Considering Nonlinear Cornering Behavior

The driver of a vehicle has a significant influence on handling and stability of the vehicle. Due to the complex behavior of a human pilot, a driver model is usually neglected when dealing with the problem of vehicle stability. This work focuses on the interaction between the vehicle and the human pilot. A model characterizing human operator behavior in a regulation task is employed to study directional stability. Linear stability is analyzed by the application of the Routh-Hurwitz criterion and stability boundaries separating the stable domain of operation of the driver from the unstable one are constructed.

The linear analysis predicts that the only possible instability in a driver/vehicle system is an oscillatory instability with increasing amplitude. It is shown that the addition of kinematic as well as slip angle nonlinearities in the vehicle model can have a stabilizing effect on these oscillations of the combined driver/vehicle system. They may also be responsible for the opposite, namely a linearly stable motion may become unstable to finite size disturbances. These nonlinear motions are predicted by a bifurcation analysis and are verified by direct numerical simulation.     

Raising commuter parking prices — An empirical study

Recently, management of parking rates has been proposed as an effective policy option to ameliorate the adverse impacts of excessive commuter automobile use in urban areas. Parking price strategies have the potential for significantly altering travel behavior in favor of high occupancy vehicles, as well as reducing congestion, energy consumption and pollution. Unfortunately, however, a paucity of empirical evidence exists regarding the impacts of parking pricing policies on travel patterns. The recent attempt aimed at eliminating federal employee parking subsidies provided a unique opportunity to take a careful look at the impacts of commuter parking price increases.In November 1979, federal employees at many government facilities in Washington, DC, and other major cities began to pay one-half of nearby commercial parking rates for government-controlled parking spaces. This paper presents the impacts of the parking price increases on commuting behavior at a sample of 15 worksites in metropolitan Washington, DC, and discusses their short term planning and policy implications. A before and after with control group survey design monitored the effects on modal shifts, automobile occupancy, and parking behavior. The results showed that removing free parking and raising parking rates (from $10 to $32 per month) influenced some significant shifts to higher-occupancy modes, but that the shifts were not uniform in direction or magnitude across the sites. In addition, the study examined how locational, travel, and employee factors influenced the modal shifts.     

The experience of express coach deregulation in Great Britain

This paper reviews the effect of express coach deregulation in Britain following the Transport Act 1980. The authors have monitored the range of services offered before and after the Act, using operators' literature, roadside surveys, on-vehicle passenger interviews and interviews with operators as sources of information. These are used to present an overall picture of express deregulation, with particular reference to changes in real fare levels, and also the relative importance of competition within the coach industry compared with that of inter-modal competition (that between coach and rail). The latter has emerged as more significant.The greater part of the paper is devoted to analysis of the long-distance market but the development of commuter coach services into central London is also examined, together with the reasons why independent operators have secured a larger share of this market.     

Efficient solution algorithm for finding spatially dependent reliable shortest path in road networks

Travel times are generally stochastic and spatially correlated in congested road networks. However, very few existing route guidance systems (RGS) can provide reliable guidance services to aid travellers planning their trips with taking account explicitly travel time reliability constraint. This study aims to develop such a RGS with particular consideration of travellers' concern on travel time reliability in congested road networks with uncertainty. In this study, the spatially dependent reliable shortest path problem (SD‐RSPP) is formulated as a multi‐criteria shortest path‐finding problem in road networks with correlated link travel times. Three effective dominance conditions are established for links with different levels of travel time correlations. An efficient algorithm is proposed to solve SD‐RSPP by adaptively using three established dominance conditions. The complexities of road networks in reality are also explicitly considered. To demonstrate the applicability of proposed algorithm, a comprehensive case study is carried out in Hong Kong. The results of case study show that the proposed solution algorithm is robust to take account of travellers' multiple routing criteria. Computational results demonstrate that the proposed solution algorithm can determine the reliable shortest path on real‐time basis for large‐scale road networks. Copyright © 2016 John Wiley & Sons, Ltd.     

特长高速公路隧道通风斜井钢波纹板式中隔墙技术研究北大核心CSCD

通风导洞中隔墙一般采用技术较为成熟的混凝土中隔墙,但存在表面粗糙、工艺复杂、施工进度不易控制等缺点,无法适用于风道较为复杂的工程。文章以东天山隧道1号斜井为依托,提出了节能型全拼装式钢波纹板中隔墙技术,通过数值模拟以及理论计算的方法验证其在单洞四风道通风斜井中的可行性。研究结果表明:钢波纹板式中隔墙增大了斜井有效通风截面积,断面风速降低约5.3%,同时大幅减小通风斜井内的沿程阻力,仅为既有混凝土墙方案的17%左右;拱顶变形及二次衬砌混凝土结构受力均远低于结构安全限值。该技术克服了传统钢筋混凝土中隔墙的缺点,在满足隧道通风防灾要求的同时,改善了隧道施工环境,且施工工期可缩短为原方案的三分之一。     

铁路隧道钻爆法机械化修建设计关键技术北大核心CSCD

隧道钻爆法机械化修建方法是以全工序高效率大型机械配套为基础,用以解决复杂山区长大山岭隧道安全、优质、高效及经济等施工问题的一种技术方法。文章从隧道设计角度论述了钻爆法机械化修建面临的掌子面安全控制与洞身段变形控制两大关键挑战,并总结了以机械化全断面全地质型施工技术、掌子面稳定性评价方法、掌子面超前主动支护技术、掌子面超前支护“定量化”精准设计技术、低预应力锚杆主动支护技术、早高强喷混凝土主动支护技术、初期支护快速成环封闭技术、围岩形变压力计算方法等为核心的隧道钻爆法机械化修建设计关键技术,为推广应用隧道钻爆法机械化修建方法提供技术支撑。     

Determinants of certified motorcycle helmet use among postal delivery riders at rural areas in Peninsular Malaysia

This study aims to identify the determinants of certified helmet use among postal delivery riders (PDRs) in rural areas of Peninsular Malaysia. A cross-sectional study was done among 269 PDRs from 50 postal distribution centres (DC) nationwide. Data collection was achieved through observation of the helmets and a questionnaire. The quality of the motorcycle helmets was determined by the presence of the certification label issued by the Standards and Industrial Research Institute of Malaysia (SIRIM). The response rate was 99.3%. The odds of full-shell helmets having the SIRIM label were 37.1 times more than that of the half-shell helmets. The odds of non-purchased helmets having the SIRIM label were 14.9 times more than that of the purchased helmets. The odds of expensive helmets having the SIRIM label were 4.4 times more than that for cheaper motorcycle helmets. The odds of helmets owned by riders without a previous crash history having the SIRIM label were 1.9 times more than helmets owned by riders with a crash history. Full-shell helmets with SIRIM standard certification, non-purchased helmets, helmet price of US$11.00 or more, and motorcycle riders without any previous crash history were determinants that contributed towards the use of a certified motorcycle helmet. Multiple logistic regression indicated that two variables significantly predicted the use of a certified motorcycle helmet among PDRs – helmet type and cost. An employer that provides the employees with full-shell motorcycle helmets with SIRIM standard certification label that costs at least US$11.00 and hiring motorcycle riders without any previous crash history gives a higher chance of compliance with standard certified motorcycle helmet usage.     

采用自动识别系统对水下输气管线、离岸平台和船舶检验评分的实时监测（英文）

The aim of this research is to develop an algorithm and application that can perform real-time monitoring of the safety operation of offshore platforms and subsea gas pipelines as well as determine the need for ship inspection using data obtained from automatic identification system(AIS). The research also focuses on the integration of shipping database,AIS data, and others to develop a prototype for designing a real-time monitoring system of offshore platforms and pipelines. A simple concept is used in the development of this prototype, which is achieved by using an overlaying map that outlines the coordinates of the offshore platform and subsea gas pipeline with the ship's coordinates(longitude/latitude) as detected by AIS. Using such information, we can then build an early warning system(EWS) relayed through short message service(SMS), email, or other means when the ship enters the restricted and exclusion zone of platforms and pipelines. The ship inspection system is developed by combining several attributes. Then, decision analysis software is employed to prioritize the vessel's four attributes, including ship age, ship type, classification, and flag state.Results show that the EWS can increase the safety level of offshore platforms and pipelines, as well as the efficient use of patrol boats in monitoring the safety of the facilities. Meanwhile, ship inspection enables the port to prioritize the ship to be inspected in accordance with the priority ranking inspection score.