Identification of hydrodynamic forces on a flexible pipe near plane boundary subjected to vortex-induced vibrations

Formally,use of system identification techniques to estimate the forces acting on the beam may give information on hydrodynamic forces due to vortex-induced vibrations(VIVs),but no results from such attempts for submarine pipeline spans have been reported.In this study,a pipe model with a mass ratio(mass/displaced mass) of 2.62 is tested in a current tank.The gap ratios(gap to pipe diameter ratio) at the pipe ends are 2.0,4.0, 6.0 and 8.0.The response of the model is measured using optical fiber strain gauges.A modal approach linked to a finite element method is used to estimate the hydrodynamic forces from measurement.The hydrodynamic force at the dominant response frequency is the major concern,and the lift force and added mass coefficients are calculated.Response calculations are performed using force coefficients from the inverse force analysis and the calculated results are in accordance with the experimental data.     

Introducing Willingness‐to‐pay for Noise Changes into Transport Appraisal: An Application of Benefit Transfer

Abstract

Numerous research studies have elicited willingness‐to‐pay values for transport‐related noise. However, in many industrialized countries including the UK, noise costs and benefits are still not incorporated into appraisals for most transport projects and policy changes. This paper describes the actions recently taken in the UK to address this issue, comprising: primary research based on the city of Birmingham; an international review of willingness‐to‐pay evidence; the development of values using benefit transfers over time and locations; and integration with appraisal methods. Amongst the main findings are: that the willingness‐to‐pay estimates derived for the UK are broadly comparable with those used in appraisal elsewhere in Europe; that there is a case for a lower threshold at 45 dB(A)Leq,18h rather than the more conventional 55 dB(A); and that values per dB(A) increase with the noise level above this threshold. There are significant issues over the valuation of rail versus road noise, the neglect of non‐residential noise and the valuation of high noise levels in different countries. Conclusions are drawn regarding the feasibility of noise valuation based on benefit transfers in the UK and elsewhere, and future research needs in this field are discussed.     

Social Media Use during Unplanned Transit Network Disruptions: A Review of Literature

Abstract

This paper explores social media's role in managing unplanned transit networks disruptions. Although literature exists more broadly on the use of social media in transit, this paper presents the first literature review in this setting. When disruptions occur, commuters require reliable, up-to-date information. Its provision reduces anxiety and allows informed choices. Social media is beneficial given it provides real-time information but it can only supplement (not replace) conventional approaches. Information reliability was critical. Research in the field of disaster management illustrates the importance of publicly contributed information. Known as “crowdsourcing”, it is part of the emerging field of crisis informatics which for the first time was linked to unplanned transit disruption management. The results highlight that social media's real-time nature can reduce disrupted travel demand; however, its utilisation can be resource-intensive. A framework presented illustrates how social media utilisation varies according to the operational characteristics of a disrupted network. Social media use as an information delivery tool is still in its infancy and an unwillingness to embrace it is an impediment to sustained growth. Crowdsourcing is one approach that could resolve the issue of transit agency resourcing whilst satisfying the increased demand and expectation for real-time information.     

一种基于手机定位数据的出行行程识别方法

提出并实现了一种基于手机定位轨迹数据的出行行程识别方法.通过速度对轨迹点进行划分,将低于一定速度阈值以下的轨迹点合并为候选停留位置,再利用距离阈值和时间阈值对候选停留位置进行合并,从而确定出真正的停留点,继而自动统计出行次数和出行时间.该方法解决了手机定位数据的定位漂移和抖动的问题,行程识别精度高,识别结果可为交通规划工作提供相关数据,并具有比传统交通调查方法更低的成本和更短的数据更新周期.     

交叉口配时方案实时优化与仿真系统研究

为了充分利用交叉口的时空资源,缓减拥挤,根据单交叉口的实时检测器数据,基于优化模型和仿真模型,以均衡交叉口的交通压力目标,开发了一款交叉口配时方案实时优化与仿真系统,来对配时方案中的周期、绿信比、相序进行动态优化.实测结果表明,与传统定时信号控制方式相比,优化后的交通信号配时控制效果更好,车辆平均延误时间更少.     

汽车PEPS系统诊断测试的应用与研究

随着汽车技术的不断提高,汽车PEPS系统也对其诊断测试结果的速度、准确性、连续性提出了更高的要求,利用Vector公司开发的CANoe总线仿真软件,对各种车身电子模块进行模拟,建立具有改进AES算法认证加密的汽车PEPS系统的测试仿真环境。实际测试结果表明,该系统不仅可以在虚拟节点下进行模拟仿真测试,也可以在真实节点下进行实时测试,灵活有效地反映出汽车PEPS系统中各种电子模块的总线通信情况,同时保证了故障诊断测试连续性和有效性。     

CY8800舰船网络自动化系统可靠性设计

本文论述了以多重冗余设计的微机局域网络应用于舰船控制系统中的可靠性,介绍了以此为原则设计的CY8800系统。CY8800系统采用改进的星形网络,即双重树形实时网络,该网络具有节点双重冗余设计,分级树形结构和网络服务器分散到各节点等特点,其可靠性和抗干扰性高。本文还简略介绍了CY8800系统中的控制级、操作级和管理级微机的特点和功能,最后计算分析了CY8800系统的可     

基于AD/RTS仿真计算机的多任务调度方法研究

近些年由于并行处理机和并行算法的大量应用，建立在并行机与并行算法上的各种调度方法逐渐成为研究的热点问题。主要研究基于实时多处理机系统中对任务如何合理分配以达到提高各处理器的利用率目的的方法。首先介绍了并行机与并行算法，以及各种实时调度算法，然后通过对静态和动态调度方法的研究，基于ADI计算机进行鱼雷控制系统仿真的实时调度方法实验，并分析了实验结果。     

拉绳式位移传感器在江阴大桥结构健康监测中的应用

结合江阴长江公路大桥结构健康监测系统升级改造项目,采用拉绳式位移传感器实时监测大桥主梁的纵向运动,并依据实测数据进行梁端位移变化和运动同步性的统计分析。结合突发船撞事件,采集撞击下的大桥位移响应和结构激励状态信息,评价大桥受撞击后的结构损伤和工作性能,得出结论认为此次撞击对主梁的损伤较小,并且大桥运营近6年来主桥钢箱梁结构的刚度并没有发生明显劣化。     

公路网事故多发段(点)判别方法研究

针对在事故多发段判别时,平面交叉节点通处理为路段,平面交叉节点的安全重要性被弱化,判别精度受到了影响的问题;并针对路网事故多发段判别时,先判别事故严重的路,再判别其上事故多发段,忽略了整体事故不严重的路上个别事故多发的段点的问题。对路网中各种等级公路进行归一化处理;根据平面交叉节点行车安全特性,把公路划分为平面交叉节点路段和普通路段;平面交叉节点路段安全影响范围的确定;从而进行路网事故多发段判别。既提高了已有动态步长过滤法等对一条公路进行事故多发段判别的精度,又解决了不同等级、不同特征公路组成的路网在同一水平下的事故多发段判别;为路网安全管理提供了基础。