空泡水筒中螺旋桨模型试验的筒壁影响和修正

在中国船舶科学研究中心工作段直径为0.8米的水筒中,试验了三个几何相似的螺旋桨模型。用激光测速仪测量了螺旋桨前后不同截面的水筒流速分布,也测量了筒壁上的压力分布。对水筒中进行无空泡、有空泡和超空泡螺旋桨试验时,应如何进行筒壁影响的修正,提供了依据。同时还指出,水筒中螺旋桨的推力或负荷系数与水池敞水试验值相同时,其流场仍然是不同的。     

Dynamic Performance of a Bulkhead Flat Car

The dynamic performance of a flat car is studied herein. The performance indices include roll angles, lateral accelerations, center plate loads, side bearing loads, wheel loads and spring deflections. These variables are maximum when the car is running at its critical speed, corresponding to either the rock and roll, or the bounce mode. The Association of American Railroads' (AAR) Flexible Carbody Model was used. The input for vertical track irregularities used in the simulation was generated from published spectra for U.S. Federal Railroad Administration (FRA) Class 4 track. After studying the car's performance with various column loads and spring suspensions, it was found that the most commonly used column load of 4,000 lbs. (17.8 kN) should be used. The spring suspension used in the original car design should also be adopted, in order to avoid spring. bottoming.     

Analysis of the optimal length of road expansion – A case study of the Taipei metropolitan area

This study explores the optimal investment in the length of an expanded section of road to mitigate the congestion on a transportation corridor. It is assumed that one end of the road is in the central business district (CBD) and that the households are uniformly distributed along the road. Each individual makes trips from his/her residence to the CBD. Trip demand is elastic and depends on the cost of the trip (including congestion costs). During the first stage, the government determines the length of the expanded section given the width of that section. In the second stage, road users determine their trip demands by taking into consideration the trip cost function. In the process of solving this problem, the equilibrium traffic volume is first solved using differential equations. The optimal length of the expanded section is then solved by maximizing the social welfare. The analysis is then applied to the case of the Tucheng city – Banciao city – Taipei CBD corridor in the Taipei metropolitan area. The scheme of road expansion without tolling performs closely to the first-best scheme for the case of a high potential demand. This study’s approach can serve as valuable reference for city planners engaged in road planning in a transportation corridor between the CBD and satellite cities in a metropolitan area.     

Evaluating parking reservation policy in urban areas: An environmental perspective

This paper investigates a parking reservation mechanism to reduce car cruising to find parking. To consider the benefits for drivers and parking facility providers, we charge drivers for making reservations in addition to parking fees, by introducing a reservation pricing model that makes reservation prices equivalent to the value of saved search time. By modeling the number of vacant spaces as a stochastic variable, and applying binomial pricing methods, parking reservation prices are obtained. Numerical examples based on the data for two parking facilities in Taiwan are given.     

Allocation flexibility and price efficiency within Singapore’s Vehicle Quota System

Permit or license plate quotas are highly effective albeit controversial policy tools for managing growth in the vehicle population and thereby, adverse traffic congestion. A judicious distribution of the scarce permits that targets the dual objectives of price efficiency and social diversity in vehicle ownership can however mitigate the controversy. This paper scrutinizes the attainment levels of these two objectives within Singapore’s multi-categorical Vehicle Quota System in two time periods (1991–1998 and 2002–2011) which differ in the number of permit allocation categories, the auction format used (sealed versus open bids) and in the frequency of distribution (monthly versus semimonthly). The lessons derived are contrasted to the other two jurisdictions which have also implemented quotas on their vehicle registrations namely, Shanghai and Beijing.     

Aggregates cranes handling capacity of container terminals: the port of Kaohsiung

This study looks at the degrees of interference for multiple cranes that work simultaneously at six major container terminals in the port of Kaohsiung. The results confirm that there are different degrees of mutual crane interference among terminals where different operational modes are adapted in the container yards. RTG handling systems show a very high value of aggregate cranes exponent f, with nearly no interference, as long as the number of allocated cranes is no more than the number of truck lanes under each crane. While SC systems reveal a relatively larger degree of mutual interference as the number of cranes increase.     

基于ADAMS的麦弗逊前悬架优化设计

汽车悬架系统为一多体系统,部件之间的运动关系十分复杂,传统的人工计算很难将悬架的各种特性表述清楚。以多刚体系统动力学理论为基础,应用机械系统动力学仿真分析软件ADAMS中的Car专业模块建立该车的麦弗逊式前悬架多刚体模型,并采用ADAMS/Insight模块进行参数分析,同时进一步进行悬架布置的优化,在一定程度上提高了整车的行驶平顺性和操纵稳定性性能。     

基于燃烧室形状的柴油机排放特性数值模拟分析

在固定柴油机压缩比和燃烧室容积的前提条件下,提出通过改变燃烧室缩口率及内部形状,实现柴油机各排放生成物量变的研究思路.运用汁算流体动力学(CFD)分析方法,对所设计的3种不同的燃烧室进行缸内工作过程的仿真分析,得出不同形状的燃烧室对缸内气相流场、温度场及排放生成物的影响规律.     

基于多功能航标的海事监管模式的研究应用

传统海事监管以人员查询、船舶报告为主,数据获取手段单一,信息处理水平较低,存在监管时效性差等局限.针对上述问题,结合航道内广泛布设的航标,以多功能航标数据的采集、存储、分析和应用为基础,融合现有的海事监管信息,提出一种基于多功能航标的海事监管模式,从而推进海事监管信息化建设,提高监管效率,使内河海事监管现场化、实时化.通过实验验证,多功能航标信息系统运行稳定,在实时获取数据、辅助海事监管方面取得良好效果.     

常州城市设计水位建议值研究报告

介绍了常州城市设计水位建议值研究中综合的各因素。常州城市河道通航、防洪、建桥、取水、供水、排水、农田水利及控制城市临介地坪标高等均具有统一要求,该水位建议值可统一常州城市设计水位,确保达到预期效果和所指定的安全标准,具有应用价值。