Optimization for Vehicle Suspension I: Time Domain

A numerical procedure for finding the optimum values of a number of parameters describing a model vehicle suspension has been studied. The vehicle has been modelled by dynamic systems of linear springs and dampers, and the goal is to obtain lower acceleration peaks at an elected design point in the vehicle.

The problem is stated as a mathematical programming problem which can be solved by means of the sequential linear programming technique. The procedure has been implemented for a four wheel independent suspension model capable of being subjected to road irregularities and to centrifugal and braking accelerations.     

Vehicle/Pilot System Analysis: A New Approach Using Optimal Control With Delay

This article deals with the simulation of a vehicle/pilot system experiencing external disturbances. In the simulation, the car is modeled with two degrees of freedom and the pilot is assumed to respond to the state vector with a time delay. When perturbations are introduced, the pilot is expected to drive his car back to the initial state while minimizing a quadratic cost function. With some simplifications for low frequencies responses, the model is then used to simulate the response of different vehicles to an initial step in lateral displacement. The results from the simulations are interpreted in the light of the controllability diagrams.     

The role of accident exposure in transport system safety evaluations II: Group exposure and induced exposure

Part I of this paper has argued that any meaningful evaluation of transport system safety must include a consideration of the exposure to accidents, and has demonstrated the use and limitations of several measures of exposure at intersections and along links of the network. To complement this treatment of site exposure, this part of the paper will describe the use of group exposure measures in the assessment of risks incurred by people within particular population groupings. The use of induced exposure measures is also briefly reviewed.     

保持交通运营扩宽Montedomini隧道:Nazzano工法的演化

在2000年初的Nazzano隧道(A1高速,毗邻罗马)扩宽工程中,首次尝试在不影响既有交通的情况下进行高速公路隧道的扩宽,而非更改线路或采用施工中降低隧道交通服务水平的方法。该工程证明了Nazzano工法的可行性和有效性,采用该工法最大限度地减少了土地占用量,在扩展干线公路、高速公路或铁路基础设施能力时,在建筑施工期间能够不降低其服务水平。由于其他方案(如开挖第3条隧道或在加宽车道处封闭交通)将增加更多的经济和社会成本,因而这种能够不干扰交通的隧道扩宽方案已成为投资方一种可靠有利的选择。     

Multi-objective signal control of urban junctions – Framework and a London case study

This paper presents an approach to multi-objective signal control using fuzzy logic. The signal control uses fuzzy logic where the membership functions are optimised according to the Bellman–Zadeh principle of fuzzy decision-making. This approach is both practical for the decision-maker and efficient, as it leads directly to a Pareto-optimal solution. Signal control priorities are ultimately a political decision. Therefore the tool developed in this research allows the traffic engineer to balance the objectives easily by setting acceptability and unacceptability thresholds for each objective. Particular attention is given in the example to pedestrian delays. The membership functions of the fuzzy logic are optimised by a genetic algorithm coupled to the VISSIM microscopic traffic simulator. The concept is illustrated with a case study of the Marylebone Road–Baker Street intersection in London at which pedestrians as well as vehicle flows are high. The results prove the feasibility of the framework and show the vehicle delays for a more pedestrian friendly signal control strategy.     

New tension mechanism for high-speed tensile testing machine

As concerns of dynamic tensile measuring, a new tension mechanism driven by liner motor in high-speed tensile testing machine is presented. It satisfies the requirements for testing the dynamic tensile properties of plastic materials with strain rates from 1 to 100 s^-1, which is relatively difficult to test for currently available machines. For this purpose the idle stroke principle is used to realize the dynamic load of plastic material with static grip. Computer aided engineering is used: i) to analyze and optimize the tension mechanism thus allowing reducing the system shock caused by collisions. ii) to avoid the influence of plastic materials specimen stress and strain uniformity on the measuring system. The analysis results agreed well with the established empirical relationships based on experimental evidence. Two sets of experiments for different strain rate tensile were conducted thus allowing proving the reliability and credibility of the designed tension mechanism.