《城市道桥与防洪》投稿须知

<正>《城市道桥与防洪》杂志是一份面向全国城市交通、道路、桥梁、防洪和排水工程界的科技期刊技术类刊物,是一份理论和实践相结合的实用性很强的刊物。主要报道城市交通、道路、桥梁、防洪、排水工程的教学、科研、勘察、设计、施工、养护、管理、产品生产以及公路、铁路、港口、水利系统相关领域的新技     

《城市道桥与防洪》投稿须知

<正>《城市道桥与防洪》杂志是一份面向全国城市交通、道路、桥梁、防洪和排水工程界的科技期刊技术类刊物,是一份理论和实践相结合的实用性很强的刊物。主要报道城市交通、道路、桥梁、防洪、排水工程的教学、科研、勘察、设计、施工、养护、管理、产品生产以及公路、铁路、港口、水利系统相关领域的新技     

《城市道桥与防洪》投稿须知

<正>《城市道桥与防洪》杂志是一份面向全国城市交通、道路、桥梁、防洪和排水工程界的科技期刊技术类刊物,是一份理论和实践相结合的实用性很强的刊物。主要报道城市交通、道路、桥梁、防洪、排水工程的教学、科研、勘察、设计、施工、养护、管理、产品生产以及公路、铁路、港口、水利系统相关领域的新技术、新工艺等最新科研成果,我们竭诚欢迎从事这些行业的广大科技人员踊跃投稿。     

《城市道桥与防洪》投稿须知

<正>《城市道桥与防洪》杂志是一份面向全国城市交通、道路、桥梁、防洪和排水工程界的科技期刊技术类刊物,是一份理论和实践相结合的实用性很强的刊物。主要报道城市交通、道路、桥梁、防洪、排水工程的教学、科研、勘察、设计、施工、养护、管理、产品生产以及公路、铁路、港口、水利系统相关领域的新技术、新工艺等最新科研成果,我们竭诚欢迎从事这些行业的广大科技人员踊跃投稿。     

《城市道桥与防洪》投稿须知

<正>《城市道桥与防洪》杂志是一份面向全国城市交通、道路、桥梁、防洪和排水工程界的科技期刊技术类刊物,是一份理论和实践相结合的实用性很强的刊物。主要报道城市交通、道路、桥梁、防洪、排水工程的教学、科研、勘察、设计、施工、养护、管理、产品生产以及公路、铁路、港口、水利系统相关领域的新技     

老百姓的CAFE情节 力帆KP150改装版街拍

皮衣客、雪茄客、嬉皮士、朋克、爱丽丝、NEWSCHOOL、OLDSCHOOL、小年轻、老头子、男同志、女萝莉、高富帅、白富美、吊丝男、拜金女、金属狂人、咬着奶嘴的小宝贝、控制不住心跳的绿巨人、刚刚沉浸在恋爱中的情侣、内裤穿外面就能飞的美国超人。     

逆变器、PLC在卸船机上的应用

逆变器、PLC在国内外已广泛应用于钢铁、石油、化工、电力、建材、机械制造、汽车、轻纺、交通运输、环保及文化娱乐等各个行业.文中介绍整流回馈、逆变器、PLC在卸船机上的应用,重点介绍了整个系统的构成、软硬件特点和关键点.     

新书速递

《为自由招魂》收录李敖先生的著述较丰富、全面。为尽可能保持李敖先生著述的全貌和原貌,文章只字未删。本书包含:记一位没有"流血的自由"的先烈、漫画的自由意义、不拍马屁的自由、梦做骆马的自由、论唱反调、"敢怒而又敢言"的自由、独裁中的民主、张宗昌,我梦到了你、开玩笑的自由、没有演说的自由、月亮属于谁的、我们梦想"野蛮之自由"、读警总秘密会议记录、秘雕案的案外意义、还是第一声最像、"春风吹又生"、肚皮里的言论自由……     

《城市道桥与防洪》投稿须知

<正>《城市道桥与防洪》杂志是一份面向全国城市交通、道路、桥梁、防洪和排水工程界的科技期刊技术类刊物,是一份理论和实践相结合的实用性很强的刊物。主要报道城市交通、道路、桥梁、防洪、排水工程的教学、科研、勘察、设计、施工、养护、管理、产品生产以及公路、铁路、港口、水利系统相关领域的新技术、新工艺等最新科研成果,我们竭诚欢迎从事这些行业的广大科技人员踊跃投稿。     

《城市道桥与防洪》投稿须知

<正>《城市道桥与防洪》杂志是一份面向全国城市交通、道路、桥梁、防洪和排水工程界的科技期刊技术类刊物,是一份理论和实践相结合的实用性很强的刊物。主要报道城市交通、道路、桥梁、防洪、排水工程的教学、科研、勘察、设计、施工、养护、管理、产品生产以及公路、铁路、港口、水利系统相关领域的新技术、新工艺等最新科研成果,我们竭诚欢迎从事这些行业的广大科技人员踊跃投稿。     

Frequency Response Analysis of Canadian Logging Trucks

SUMMARY

This paper examines the frequency responses often logging truck configurations currently operating in the interior of British Columbia in Canada. The work is an extension of a previous study conducted at the National Research Council (NRC) in 1990. The previous study presented an extensive analysts of the directional responses and frequency responses of four Canadian log-hauling truck configurations; a tractor/pole trailer, a tractor/triaxle trailer, a tractor/quadaxle trailer (with a single load), and a tractor/single-axle-jeep/pole trailer. In the current study, the frequency responses of these four configurations are compared with those of six more log-hauling truck configurations; a tractor/ tandem-axle-jeep/pole trailer, a doglogger, a double doglogger, a tractor/quadaxle trailer (with a dual load), a tractor/jeep/triaxle trailer, and a tractor/jeep/quadaxle trailer. The current study makes use of three models developed by NRC in the previous study, and a new model developed at NRC in cooperation with the University of Victoria.

The frequency response method has been applied in this study to predict the lateral acceleration at the centre of gravity of each articulated vehicle unit, and the rearward amplification ratio. The logging truck simulation results have been compared with corresponding results, obtained using UMTRI's simplified models, for three conventional highway vehicles; a tractor/semitrailer, a B-train, and an A-train. The comparison provides a useful indication of the differences between the behaviours of logging trucks and conventional highway trucks in their shared environment.     

基于频率法的索力测量系统

为了在工程现场快速方便地检测斜拉桥的拉索索力,依据随机振动法索力检测原理,开发了一种新型的索力测量系统。通过对随机振动法索力检测方法的概述,介绍了该系统的性能、硬件结构和软件模块,并重点阐述了通过数字滤波抑制快速傅里叶分析(FFT)的混频现象、自动扫描确定主振频率和提高索力计算精度的方法和措施。索力测量系统以AT89C55WD单片机(SCM)为平台,集成了电荷放大器、信号分析仪和计算器的相关功能。在工程现场,只需输入少量参数,拉索振动信号采集、信号的快速傅里叶分析和对应的索力计算即可在线自动完成。     

面向交通枢纽的车辆三维真实感实时仿真

为分析和解决城市交通拥挤问题并提高城市道路利用率提供可行的途径,提出了一种面向交通枢纽的车辆运行仿真方法,通过场景、道路与车辆的三维动态建模,实现交通枢纽交通状况的实时真实感仿真.首先,提出了基于道路关键点连接网络模型表示交通枢纽的通行道路.其次,基于粒子系统实现车辆的动态运行实时仿真,并采用基于空间剖分的车辆碰撞检测方法对车辆运动控制算法进行了优化.最终,通过对路段的动态观测和反馈机制实现车辆行驶路线的规划和调度.实验结果表明,本文提出的方法可以生动直观地呈现实际路面的交通状况,并且能以较为流畅的帧速率实现交通场景的动态仿真.     

考虑溶洞空间形态的路基岩溶顶板稳定性分析方法

岩溶路基随岩溶地区交通工程建设的快速发展而越来越普遍,如何评价岩溶路基稳定性成为岩溶区路基设计与施工的关键问题之一。针对目前路基岩溶顶板稳定性分析的不完善性,考虑溶洞形成过程中岩溶顶板所具有的空间形态特征,首先,将路基下伏岩溶顶板简化为固支梁、抛物线拱、圆拱与固支双向板等承载模型,以此进行路基岩溶顶板稳定性分析,并采用结构力学分析理论分别建立不同模型的路基岩溶顶板抗弯最小安全厚度计算方法;其次,通过典型案例的影响因素敏感性分析,揭示岩溶顶板最小安全厚度随溶洞顶板矢高、跨度、岩石抗拉强度与上覆荷载的变化规律,探讨路基岩溶顶板破坏模式的控制性因素及其影响规律,确定岩溶路基稳定性分析的基本原则;然后,基于岩溶地区地质勘察信息提出路基岩溶顶板稳定性分析过程,建立考虑溶洞空间形态特征的路基岩溶顶板稳定性分析方法;最后,通过工程实例计算分析验证所提方法确定的路基岩溶顶板稳定性评价结果的合理性与有效性。研究结果表明：岩溶顶板按何种模式破坏不仅与破坏形式有关,还与溶洞形态及其矢高密切相关,石灰岩抗拉强度同样影响较大,工程设计与稳定性评价时应基于勘测数据分析各种破坏模式,以便使设计或评价结果更接近实际情况。     

一种新型双动双腔真空增压器

EQ1060F轻型载货汽车的制动系统最初采用单腔制动总泵加单真空增压器及安全缸的半双管路结构。为了提高安全性，后采用双膜片真空助力器的双管路结构。为了适应使用要求，又改为两个真空增压器的方案，但仍存在结构复杂、接头环管多、易泄漏、自由行程过大，超载行驶时，感到制动力不足等问题。现采用一种新设计方案，以双腔制动总泵输出油压为控制源，用真空动力缸为增压机构，以双进、双出、双活塞的泵体为辅助缸，实现单真空增压器的双管路系统。     

Dynamic analysis of a pantograph-catenary system using absolute nodal coordinates

The dynamic interaction between the catenary and the pantographs of high-speed trains is a very important factor that affects the stable electric power supply. In order to design a reliable current collection system, a multibody simulation model can provide an efficient and economical method to analyze the dynamic behavior of the catenary and pantograph. In this article, a dynamic analysis method for a pantograph-catenary system for a high-speed train is presented, employing absolute nodal coordinates and rigid body reference coordinates. The highly flexible catenary is modeled using a nonlinear continuous beam element, which is based on an absolute nodal coordinate formulation. The pantograph is modeled as a rigid multibody system. The analysis results are compared with experimental data obtained from a running high-speed train. In addition, using a derived system equation of motion, the calculation method for the dynamic stress in the catenary conductor is presented. This study may have significance in providing an example that a structural and multibody dynamics model can be unified into one numerical system.     

基于XGBoost的短时出租车速度预测模型

准确预测短时出租车速度是识别驾驶员异常加减速行为的前提，有助于提升乘客的安全与舒适。以城市中出租车实时移动速度为研究对象，研究了基于XGBoost的短时出租车速度预测模型。将出租车的移动速度数据集划分为训练集和测试集，构造滑动时间窗口，以时间窗口内的出租车历史移动速度的时间序列为输入变量，以出租车当前时间的移动速度为输出变量，采用前向验证的方法进行模型评估。利用基于贝叶斯算法的hyperopt模块实现模型参数的快速优化，得到模型最优参数组合，并基于深圳市2013年10月22日的出租车GPS轨迹数据集进行算例分析，将模型的预测结果与非参数回归模型、神经网络模型预测结果进行比较。研究表明:所构建的短时出租车速度预测模型的平均绝对误差（MAE）为9.841，均方根误差（RMSE）为12.711，均低于非参数回归模型和神经网络模型，提高了出租车速度的预测精度；由于出租车速度序列缺乏规律性，调整后的R₂（R₂ _adjusted）为0.592，且相较于其他2个模型，XGBoost模型在出租车速度发生急剧变化的时间点附近具有更优的拟合效果，避免了过拟合造成的预测精度下降。      

基于捕食搜索策略的混合动力汽车参数优化

混合动力汽车模型是一个较复杂的非线性系统,且设计参数较多,为一种处理燃油经济性和排放的多目标问题。文章以一辆实例样车的动力系统和逻辑门限值控制策略为例,分析并建立了以动力性能为控制约束,以最小化油耗和排放为控制目标的非线性规划模型。采用捕食搜索遗传算法,对模型进行了仿真。结果表明,该方法相对于简单遗传算法更能有效地改善车辆燃油经济性和排放。     

Les systèmes de vélos en libre-service expliquent-ils le retour du vélo en ville ?

Many French and European cities have developed a bike sharing system since 2005. This policy may be explained in a great part by the success of the Velo??v in Lyon, which contributed to improve the image of cycling in the city. If bicycles, however, appear to find a new place in the city, one can wonder whether this is really due to bike sharing systems? What are the real uses of bicycles in contemporary cities, with or without such a system? To answer these questions, the paper starts with a literature review on bicycle in the city, to draw lessons from recent experiences of bike sharing systems. It then discusses the two cases of Lyon and Lille, which never had a bike sharing system on its own. The evolution of bicycle use is measured with a comparison of household transportation surveys in Lyon (1995 and 1998) and Lille (1998 and 2006). In both cities, the analysis reveals a rise in the proportion of healthiest citizens among urban bikers, as well as a return of bikes in dense areas. Bike sharing systems are part of such tendencies. They support them, but should not become a panacea for policies supporting bike use in the city.     

Active Roll Mode Control Implementation on a Narrow Tilting Vehicle

This paper describes work carried out on the development of a narrow tilting vehicle at the University of Minnesota. The project had two objectives. One objective was to better understand the dynamics of two-passenger leaning vehicles. The other was to use this understanding to design and implement leaning control on such a vehicle. The desire was to make a tilting vehicle as easy, in some sense, to drive as a non-leaning vehicle. The scope of this work was fourfold. First, a model of such a system was developed and linearized to obtain a fourth-order linear model. Second, a tilt controller was designed to stabilize a tilting vehicle's unstable rolling mode. Third, the system and controller were simulated using both Simulink and a real time simulator written with Visual Basic. Fourth, and most importantly, an experimental vehicle was built and used for implementation. Comparisons were made between the simulated system and the experimental vehicle. This illustrated the limitations encountered in the simulations but also showed similarities that validated the model. Also, experimental results showed that the vehicle was stabilized well by the controller within the limitations of our hardware.