The Influence of Tire Factors on the Stability of Trucks and Tractor Trailers

The mechanical properties of tires and trucks are contrasted with comparable properties of the motor car to explain why the motor truck and the tractor-trailer can exhibit fixed-control instability at moderate levels of lateral acceleration. The (1) rearward bias in the distribution of roll stiffness, (2) large ratio of e.g. height to track, and (3) low torsional stiffness of the parallel-rail frame (as typically employed in heavy commercial vehicles) are found to be the major factors implicated in this phenomenon. Experimental and analytical evidence is provided to show how tire inflation pressure and mixes of (a) tire-carcass construction and (b) tread design also influence stability at moderate levels of lateral acceleration. Conclusions relating to the safety of commercial vehicle operations are drawn.     

A model for allocating car parking spaces in universities

In this paper a linear programming model has been presented for determining the optimum allocation of existing car parking facilities for different classes of users within a closed community, of which a university is a typical example.     

Design of a Stroke Dependent Damper for the Front Axle Suspension of a Truck Using Multibody System Dynamics and Numerical Optimization

Summary A stroke dependent damper is designed for the front axle suspension of a truck. The damper supplies extra damping for inward deflections rising above 4 cm. In this way the damper should reduce extreme suspension deflections without deteriorating the comfort of the truck. But the question is which stroke dependent damping curve yields the best compromise between suspension deflection working space and comfort. Therefore an optimization problem is defined to minimize the maximum inward suspension deflection subject to constraints on the chassis acceleration for three typical road undulations. The optimization problem is solved using sequential linear programming (SLP) and multibody dynamics simulation software. Several optimization runs have been carried out for a small two degree of freedom vehicle model and a large full-scale model of the truck semi-trailer combination. The results show that the stroke dependent damping can reduce large deflections at incidental road disturbances, but that the optimum stroke dependent damping curve is related to the acceleration bound. By means of vehicle model simulation and numerical optimization we have been able to quantify this trade-off between suspension deflection working space and truck comfort.     

并联混合动力汽车模糊逻辑控制策略的设计

利用模糊逻辑控制技术,设计了并联混合动力汽车的模糊逻辑扭矩控制策略。选取了控制器的输入、输出变量,构建了有25条规则的模糊推理器。在3种不同的循环工况下,分别对二值逻辑策略和模糊逻辑策略进行了仿真试验,结果显示,所设计的模糊逻辑控制策略能够很好地控制发动机工作,且具有很好的自适应能力和鲁棒性。     

湛江海湾大桥分布式健康监测系统开发研究

提出了分布式桥梁健康监测系统的原理,介绍了湛江海湾大桥分布式健康监测系统的开发情况、系统设计、硬件布置和软件功能,重点突出了数据预处理、分级传输、用户定制监测内容和分析报告,以及围绕工程养护决策需要来尽量少地布置最必要的监测内容等的研究策略。     

The impact of rail transit on land use: Evidence and a change of perspective

On the basis of available evidence we cannot clearly establish a causal relationship between rail transit and changes in land use and development patterns. At best, such changes would seem to occur only in the presence of other favorable factors, such as supportive local land use policies and development incentives, availability of developable land and a good investment climate. In any event, however, determining the precise extent of rail investment's effect on urban structure is less important than assessing the role it could play in an overall strategy for reaching larger urban goals.     

Equilibrium predictions in transportation markets: The state of the art

The task of predicting the short run equilibrium of a transportation market is central to the study of many transportation problems. In this paper we review the different approaches and methodologies that have been proposed to deal with the equilibrium problem in transportation markets. The problem is formulated in the most general way possible and its fundamental characteristics are analyzed. Then, different mathematical characterizations of transportation market and traffic flow equilibrium in networks are reviewed. Various available results are presented and analyzed. Finally, a discussion is given of alternative computational procedures for dealing with multiclass problems.     

能量法解耦在动力总成悬置系统优化设计中的运用

建立了汽车动力总成悬置系统的动力学模型,根据能量法解耦理论推导了有关公式,并将其应用到某微型车动力总成悬置系统的改进中.结果表明,对悬置刚度进行优化能有效提高解耦率,从而改善系统的NVH性能.