Search Results

A numerical method specially designed to predict unsteady aerodynamics of road vehicle was developed based on unstructured Large-Eddy Simulation (LES) technique. The code was intensively optimized for the Earth Simulator in Japan to deal with the excessive computational resources required for LES, and could treat numerical meshes of up to around 120 million elements. Moving boundary methods such as the Arbitrary Lagrangian-Eulerian (ALE) or the sliding method were implemented to handle dynamic motion of a vehicle body during aerodynamic assessment. The method can also model a gusty crosswind condition. The method was applied to three cases in which unsteady aerodynamics are expected to be crucial.

In order to investigate the possibility of noise countermeasures taken on the road and in its surroundings an urban area exposed to high road traffic noise level was taken up as a model, and their effectiveness was estimated by a hybrid simulation method combining a scale model experiment technique and a computer simulation. The case studies of simulation were carried out in the case of improving the road structures, laying the noise barriers, constructing the noise-buffer buildings and so on. As a result, more than 20 dB (A) of road traffic noise reduction were obtained by a modification of the existing surface road to an elevated road.

Controllability (C) is the parameter that determines the Automotive Safety Integrity Level (ASIL) of each hazardous event based on an international standard of electrical and/or electronic systems within road vehicles (ISO 26262). C is classified qualitatively in ISO 26262. However, no specific method for classifying C is described. It is useful for C classification to define a specific classification based on objective data. This study assumed that C was classified using the percentage of drivers who could reduce Severity (S) in one or more classes compared with the S class in which the driver did not react to a hazardous event. An experiment simulated a situation with increased risk of collision with a leading vehicle due to insufficient brake force because of brake-assist failure when the experiment vehicle decelerated from 50 km/h on a straight road.

ISO 26262 (Road vehicles - Functional safety), a functional safety standard for motor vehicles, was published in November 2011. In this standard, hazardous events associated with each item constituting a safety-related system are assessed according to three criteria, namely, Severity, Exposure, and Controllability, thereby determining ASILs (Automotive Safety Integrity Levels) representing safety levels for motor vehicles. Although motorcycles are not included in the scope of application of the current edition of ISO 26262, it is expected that motorcycles will be included in the next revision. However, it is not appropriate to directly apply ASILs to motorcycles. In the first place, the situation of usage in practice presumably differs between motorcycles and motor vehicles. Accordingly, in this research, we attempted to newly define Motorcycle Safety Integrity Levels (MSILs).

This paper is an attempt to estimate the traffic demand of private vehicles in the Philippines and Thailand toward 2030. Estimation of road traffic volume is one of the most important elements for determining fuel consumption and emission gas levels. The level of passenger car ownership is still low, but there has been a distinct shift toward passenger cars due to the lack of mass transport. In Asian countries, inspection and maintenance and emission standards are the most important policy measures. The projections of car stock are evaluated as the emissions of PM, CO and NOx by applying these policy measures in the case of Thailand.