非定常气动荷载对桥上列车行驶安全舒适性影响分析

为了研究非定常气动力荷载对桥上列车行车安全性和舒适性的影响,结合有限元软件ANSYS和多体动力学软件SIMPACK,建立列车-轨道-桥梁三维多体系统模型,计算风-列车-桥梁耦合系统的动力响应;对比分析定常与非定常气动力荷载作用下桥上列车的行驶安全与舒适性,研究非定常气动力荷载作用下不同横向风速对列车行驶安全的影响。研究结果表明:列车行驶速度为200~300km/h,无风荷载情况下,各安全性与舒适性指标值均满足要求且均小于风荷载作用。横风作用下平均风速为20 m/s,考虑非定常气动力荷载的影响不仅会使列车行驶安全评估结果更安全,还会使列车舒适性评估结果偏于保守。平均风速不超过20 m/s,车速控制在250 km/h,桥上列车行车安全、舒适性均满足要求,且平稳性等级可达到"良好"以上。通过对不同横向风速下桥上列车行驶安全分析,给出桥上列车安全行驶的阈值,为列车的安全运营提供依据。     

河口地区大型沉井基础的桥墩局部冲刷研究

桥梁水毁大多是由于桥墩局部冲刷所致，桥墩局部冲刷的预测是保证桥梁安全运行的基础，对于河口地区跨海湾的桥梁，泥沙搬运及水流运动极其复杂，且作用的水流为双向潮流和特大洪水，大多数桥墩局部冲刷公式难以运用。利用水槽物理模型试验，研究大型沉井基础入床后的局部流态及预测河床最低冲刷高程，可为工程设计参考应用。     

图像增强技术在码头水下结构外观巡检中的应用*

定期开展码头水下结构的外观巡检是码头平稳运行的重要保障。通过分析现有的检测方法，发现获取图像质量不佳是采用视觉技术实施外观巡检的主要限制条件。结合相关检测作业的要求，创新提出将人造多幅欠曝光算法与颜色通道补偿方式进行融合，并通过试验验证使用图像增强算法的水下拍摄图像的视觉质量。结果表明，多曝光与颜色补偿可有效提升水下图像的对比度、恢复细节信息并进行颜色矫正，且运算效率高；图像增强算法可有效提升水下拍摄图像的视觉质量，帮助技术人员及时识别水下结构缺陷；试验中SIFT特征点匹配数量说明提出的算法有利于后续开展缺陷的自动识别及测量研究。     

配出中性导体的IT系统负载不平衡分析

阐述了配出中性导体的IT系统特点以及与TN系统的区别,针对负载不平衡,从负序电压不平衡度、畸变率、电压波动、以及中线电流比等角度对配出中性导体的IT系统进行了分析,同时与TN系统进行对比。搭建了原型系统并进行测试,数据分析表明了IT系统配出中性导体的可行性,为进一步研究打下基础。     

Investigating the effect of travel time variability on drivers' route choice decisions in Shanghai,China

Abstract

This paper investigates the effect of travel time variability on drivers' route choice behavior in the context of Shanghai, China. A stated preference survey is conducted to collect drivers' hypothetical choice between two alternative routes with designated unequal travel time and travel time variability. A binary choice model is developed to quantify trade-offs between travel time and travel time variability across various types of drivers. In the model, travel time and travel time variability are, respectively, measured by expectation and standard deviation of random travel time. The model shows that travel time and travel time variability on a route exert similarly negative effects on drivers' route choice behavior. In particular, it is found that middle-age drivers are more sensitive to travel time variability and less likely to choose a route with travel time uncertainty than younger and elder drivers. In addition, it is shown that taxi drivers are more sensitive to travel time and more inclined to choose a route with less travel time. Drivers with rich driving experience are less likely to choose a route with travel time uncertainty.     

FRP艇艇体分段成型工艺初探

本文首先对FRP艇艇体现有的两种主流成型工艺进行了分析:手糊成型工艺;真空芯材导流工艺。提出了分段成型工艺的初步构思,以充分利用这两种成型工艺的优点。最后,对游艇分段设计的接缝形式、接缝位置、连接方式进行探讨,并提出分段连接力学分析有限元模型的思路,以缩短玻璃钢游艇的建造周期,提高生产效率。     

Evaluating the operational performance of airside and landside at Chinese airports with novel inputs

ABSTRACT

This paper evaluates the operational performance of airside and landside at Chinese airports with two novel inputs. Furthermore, the airport landside operation is decomposed into passenger-terminal operations and cargo-warehouse operations. One novel input is the capability of the runway system which is introduced into airside performance evaluation. The other novel input is cargo warehousing which is introduced into landside performance evaluation. To address multiple optimal solutions when estimating Returns to Scale in Data Envelopment Analysis, we adopted the Zhu and Shen method. This empirical study shows that neither the number of runways nor total runway length is a genuine index of runway system capability in the evaluation of airside performance. Only four airports achieved full efficiency in all eight measures while eight airports did not achieve any full efficiency. In addition, one airport did not perform well in the benchmark analysis.     

朔黄重载铁路路基病害的分类及其成灾机理研究

在大量路基病害相关文献的查阅、分析整理的基础上,结合朔黄重载铁路路基病害现场调查数据,对其存在的主要路基病害进行了分类,并对各类病害的一般特征和表现形式、产生条件及成灾机理进行了系统分析,为既有重载铁路路基病害的预防和整治措施提供理论依据和参考.     

城市公共交通优先发展立法体系国际经验

视角局限于行业层面、关注集中于单一的《城市公共交通条例》制定,是中国城市公共交通优先发展立法保障亟须解决的主要问题。分别在国家层面和城市层面选取典型案例剖析公共交通立法战略出发点、立法框架体系以及具体立法要点,为制定和完善中国城市公共交通优先发展立法体系提供借鉴。指出国家层面的立法不仅要涵盖与公共交通发展紧密相关的战略、财政、规划、运营等方面,还应与节能减排、环境保护、社会保障等领域的法律相关联;城市层面的规划与运营法规作为实施依托和补充,应强调城市差异性和可实施性。强调应构建国家、城市相互补充的多层立法体系,全方位保障中国城市公共交通优先发展战略的落实。     

广东某高速公路路堑高边坡治理工程优化设计研究

利用极限平衡法对广东某高速公路路堑高边坡原治理方案进行了天然、暴雨、地震三种状态下各工况的整体稳定性计算,在此基础上提出了优化方案,并对优化方案进行了各工况下整体稳定性验算。比选结果表明:优化方案比原方案具有安全稳定系数高且造价低的优点。