流体中弹性板声辐射阻尼研究

针对空气和水两种介质,分别研究弹性薄板的几何参数及激励位置对声辐射阻尼的影响.采用的结构振动与声场耦合的数值求解方法--有限元/流体边界元(FEM/BEM)法进行推演以及讨论结构与流体数值模拟单元.从能量的角度定义弹性板声辐射阻尼,取得声辐射阻尼的数值计算公式.利用文中的数值模拟方法对弹性例板声辐射阻尼进行计算.通过对弹性板声辐射阻尼数值模拟结果的分析认为,水中弹性板振动的声辐射阻尼远大于空气中的声辐射阻尼;相同外加激励载荷作用下,弹性薄板的板厚对相应声辐射阻尼几乎没有影响;随着板边长尺寸的增加,板的声辐射阻尼也有增大的趋势;板声辐射阻尼不随激励位置的改变而改变.     

Fare deregulation of transit services: Winners and losers in a competitive market

Currently, the Hong Kong government imposes fare control on buses and taxi while the rail services are immune to such a control. This study examined four scenarios of fare deregulation on transit services by considering three related parties of a transit system – service providers, travelers, and society in general, with their respective objectives represented as – revenue, travel utility, and congestion. Analyzing the resultant impacts on these three parties, we found that a different regulatory environment would favor or hurt a different set of parties. There is no clear win‐win situation for all parties. Deciding a socially acceptable regulatory environment is likely to involve difficult tradeoffs among these parties.     

Al-Ti-B和Ce复合添加对A356晶粒尺寸的影响

在A356铝合金中复合添加Al5TiB细化剂和稀土Ce,探讨A356铝合金的细化效果及机理。经试验发现,Al5TiB和稀土Ce对A356铝合金都有细化效果,而两者的复合添加可显著细化铝合金晶粒,并且晶粒尺寸分布更趋均匀,能达到一个更佳的效果。     

电子控制牵引力调节装置

丰田公司凌志ＬＳ４００型１９８０所型轿车装用电子控制牵引力调节有完全调节发动机的扭矩和后驱动轮的制和，并根据路面情况给出一个最佳的驱动力，它主要由制动主继电器，前轮速度传感器，牵引力调节系统执行器等１８个零部件组成，对各零部件的结构和功用进行了详细地介绍。     

Simulation of Multibody Vehicles Moving over Elastic Guideways1

This paper describes the present state of a general purpose computer program for calculating the dynamic response of vehicles travelling over guideways which may be elastic.

The linearized state-equations of motion for general multibody vehicles are constructed automatically by the program, these equations are supplemented by the equations for the active subsystems. Finally, the vehicle system equations are combined with the modal equations for elastic guideways and the complete set of coupled equations is solved simultaneously by numerical integration.     

A macroscopic taxi model for passenger demand,taxi utilization and level of services

In most urban areas taxi services are subject to various types of regulation such as entry restriction and price control. However, effective intervention depends on generating and using suitable information on the demand-supply equilibrium of the taxi market. This paper develops a simultaneous equation system of passenger demand, taxi utilization and level of services based on a taxi service situation found in the urban area of Hong Kong over the last ten years. A set of variables is introduced including number of licensed taxis, taxi fare, disposable income, occupied taxi journey time as exogenous variables and daily taxi passenger demand, passenger waiting time, taxi availability, taxi utilization and average taxi waiting time as endogenous variables. These variables are coupled together through a system of nonlinear simultaneous equations whose parameters are estimated from survey data. The simultaneous equation system can be used to obtain useful regulatory information to assist with the decisions concerning the restriction over the number of taxi licenses and the fixing of the taxi fare structure as well as a range of service quality control. This revised version was published online in June 2006 with corrections to the Cover Date.     

基于新架构的汽车远程诊断系统的应用

基于SOA(Service Oriented Architecture)新架构的汽车远程诊断系统,具有车云之间通讯的优势,使车辆具有灵活的功能选择性。本文旨在提出可以满足客户的多样化需求的、缩减整车厂车辆研发周期的汽车远程诊断系统,其具备车辆功能配置服务、体检服务以及快捷服务等功能,在提高用户满意度和体验感的同时,也可以简化整车厂同一车型子车型结构,降低相关工作量,提升整车厂工作效率。     

高速公路入口匝道多维可调模糊控制器设计

鉴于入口匝道多维模糊控制器的控制规则库会随着人们控制方面经验的增加而变得愈加复杂,从而造成规则之间的冗余性、兼容性问题.因此,给出入口匝道多维模糊控制器的解析描述,不仅有效地解决了多维模糊控制器控制规则之间的冗余性、兼容性问题,而且通过在不同状态下引入不同加权因子实现了控制器的自调整,使所设计的模糊控制器更能适应实际的高速公路交通需求.最后通过MATLAB仿真得到的结果表明,控制效果令人满意.     

SGC设计方法与马歇尔设计方法设计SMA最佳沥青用量的比较研究

分别对细、中、粗3种不同的SMA级配,采用SGC设计方法与马歇尔设计方法,设计出SMA最佳沥青用量,进行了研究比较,结果表明:SGC设计方法确定的SMA最佳沥青用量比马歇尔设计方法确定的最佳沥青用量有大幅度减少,其原因在于当采用SGC旋转100次成型混合料试件时,其压实功显著大于马歇尔双面击实50次成型的混合料试件,而我国目前的施工条件在路面难以达到相应的压实条件,易出现空隙率偏大的问题,因此建议在我国采用SGC进行SMA混合料设计时,对美国的规范进行修改,降低旋转压实的次数以适应我国的施工条件。     

摊铺机噪声测试分析

通过对某沥青摊铺机各主要声源的近场声和驾驶员耳旁噪声进行测试分析,识别出对驾驶员耳旁噪声贡献较大的噪声源.针对这些噪声源的特性采取探索性的降噪措施,使摊铺机噪声明显降低,并在此基础上提出了该摊铺机的改进建议.