New design of a road profiler

Macro and micro road profiles are of significant importance for vehicular motion studies, reliable calculations of vehicle system properties, and ensuring vehicular safety. As such, road profiles should be considered carefully. Macro profiles consider the spatial geometry of the road (curves, longitudinal and lateral slopes) while micro profiles consider roughness in longitudinal and lateral directions. These profiles have random characteristics that can be quantified under onroad and off-road conditions using a road profiler. This paper presents an analysis of a new concept for a universal profiler without gyroscopic stabilizers.     

Bridge sampling for evaluating structural impact of trucks

In this paper, a method for designing a statistically valid sample of bridges is proposed. The need for such a sampling procedure arises from the impracticality of a detailed analysis of the structural effects of new candidate truck configurations on the whole bridge inventory. In this study, a set of bridges from the national inventory was determined for the purpose of selecting a bridge sample. This set of bridges is referred to as the population. The selection of bridges for inclusion in the population was based on the status of the bridge, type of service, structural material, structural system type and functional class. The stratified sampling method was used in the determination of the required sample sizes. According to this method, the population was first divided into sub-populations, or strata. These sub-populations were non-overlapping. In turn, each strata was divided into sub-strata. The characteristics of each sub-stratum were estimated and combined to determine the characterics of the strata. Then the characteristics of the strata were combined to determine the characteristics of the bridge population. A comparison of the results based on the sample and bridge population was conducted in order to verify the validity of the proposed sampling procedure.     

Critical Review of Time-Dependent Shortest Path Algorithms: A Multimodal Trip Planner Perspective

Abstract

A multimodal trip planner that produces optimal journeys involving both public transport and private vehicle legs has to solve a number of shortest path problems, both on the road network and the public transport network. The algorithms that are used to solve these shortest path problems have been researched since the late 1950s. However, in order to provide accurate journey plans that can be trusted by the user, the variability of travel times caused by traffic congestion must be taken into consideration. This requires the use of more sophisticated time-dependent shortest path algorithms, which have only been researched in depth over the last two decades, from the mid-1990s. This paper will review and compare nine algorithms that have been proposed in the literature, discussing the advantages and disadvantages of each algorithm on the basis of five important criteria that must be considered when choosing one or more of them to implement in a multimodal trip planner.     

Experimental study on the spray and combustion characteristics of SIDI CNG

Compressed natural gas (CNG) is regarded as one of the most promising alternative fuels. In the spark-ignition (SI) engine, direct injection (DI) technology can significantly increase the engine volumetric efficiency and reduce “pumping losses” in engines without a throttle valve. DI allows engine operation with the stratified charge which enables relatively higher combustion efficiency. In this study, a combustion chamber with a visualization system is designed. The spray development and combustion propagation process of spark-ignition direct injection (SIDI) CNG were digital recorded and analyzed. The ignition probability was also examined. The results of this study can contribute important data for the design and optimization of the SIDI CNG engine.     

Powertrain system optimization for a heavy-duty hybrid electric bus

This research concerns the design of a powertrain system for a plug-in parallel diesel hybrid electric bus equipped with a continuously variable transmission (CVT) and presents a new design paradigm for the plug-in hybrid electric bus (HEB). The criteria and method for selecting and sizing powertrain components equipped in the plug-in HEB are presented. The plug-in HEB is designed to overcome the vulnerable limitations of driving range and performance of a purely electric vehicle (EV), and it is also designed to improve the fuel economy and exhaust emissions of conventional buses and conventional HEBs. Optimization of the control strategy for the complicated and interconnected propulsion system in the plug-in parallel HEB is one of the most significant factors for achieving higher fuel economy and lower exhaust emissions in the hybrid electric vehicle (HEV). In this research, the proposed control strategy was simulated to prove its validity using the ADVISOR (advanced vehicle simulator) analysis simulation tool.