Comprehensive experimental study on the effect of biodiesel/diesel blended fuel on common-rail di diesel engine technology

This research work aims to study the aspects of using biodiesel or FAME as a component blended in diesel fuel for common-rail DI engine technology. The specific engine experiments were designed for LD commercial engine [Toyota 2KD-FTV] to understand engine combustion process, engine performance and thermal efficiency when applying FAME blended fuel. In addition, the exhaust emission in HD diesel engine [HINO J08E] was evaluated by standard HD engine emission ESC and ELR test cycles. Furthermore, the severe 400-hour of HD engine durability tests for determining the limitation on using FAME blended fuel, have been conducted with B0, B10, B20 and B50. The result shows that using of FAME blended fuel in the HD common-rail DI engine, can be applied with some guidelines experimentally discovered by this research such as filter plugging that may occur when the content of biodiesel is up to 20 % or higher, and the critical fuel injector surface polishing wear, can be observed from B50 sample. In general, the higher biodiesel content will contribute to lower power output as well, thus too high biodiesel content will cause low engine power output.     

An analysis of the social context of children’s weekend discretionary activity participation

This paper examines the discretionary time-use of children, including the social context of children’s participations. Specifically, the paper examines participation and time investment in in-home leisure as well as five different types of out-of-home discretionary activities: (1) shopping, (2) social, (3) meals, (4) passive recreation (i.e., physically inactive recreation, such as going to the movies or a concert), and (5) active recreation (i.e., physically active recreation, such as playing tennis or running). The social context of children’s activity participation is also examined by focusing on the accompanying individuals in children’s activity engagement. The accompanying arrangement is classified into one of six categories: (1) alone, (2) with mother and no one else, (3) with father and no one else, (4) with both mother and father, and no one else, (5) with other individuals, but no parents, and (6) with other individuals and one or both parents. The utility-theoretic Multiple Discrete-Continuous Extreme Value (MDCEV) is employed to model time-use in one or more activity purpose–company type combinations. The data used in the analysis is drawn from the 2002 Child Development Supplement (CDS) to the U.S. Panel Study Income Dynamics (PSID). The results from the model can be used to examine the time-use choices of children, as well as to assess the potential impacts of urban and societal policies on children’s activity participation and time-use decisions. Our findings also emphasize the need to collect, in future travel surveys, more extensive and higher quality data capturing the intra- and inter-household interactions between individuals (including children). To our knowledge, the research in this paper is the first transportation-related study to rigorously and comprehensively analyze the social dimension of children’s activity participation.

A decentralized control strategy for freeway regulation

A multilevel decentralized control scheme, the cascading technique, with application to the regulation of traffic on an urban freeway is presented. Performance of the decentralized system is compared to the performance of a centralized and a fixed time control structure. It is shown that the decentralized structure performs better than the centralized structure when incidents (lane closures) occur on the freeway. The freeway is modeled in terms of the aggregate variables section density and section speed, and is considered as a system of interconnected subsystems.     

Interval constraints for the treatment of the partial data problem in gravity model calibration

The problem of indeterminacy, in the solution parameters of the Evans-Kirby calibration model, is discussed. A proposal is made to alleviate this problem, in the case of missing data, by introducing interval constraints.     

Simulation of fixed route bus travel time

Travel time on fixed route urban bus route is discussed. Given that the travel time is a function of three basic variables, Monte Carlo procedure is used to simulate trips during a specific time interval. Each variable is assumed to have a specific probability distribution with known or estimatable parameters. It is shown that this micro-computer simulation model can be used for examining the effects of traffic management schemes, number of stops and passenger demand on travel time, and subsequently fleet size and level of service.     

The effect of round-off error on computed solutions of trip distribution problems

Round-off error analyses of two versions of the Kruithof method are given. It is shown than an alternative implementation is numerically superior to the usual implementation. Since it also has the advantage of requiring less writing in secondary memory, and requires the same number of arithmetic operations, the case for always using the alternative implementation seems indisputable.     

Does regional travel time unreliability influence mode choice?

Researchers and practitioners highlight the unreliability of travel as a potential weak link in the transportation system which may inhibit individuals’ accessibility and urban economic activity. With the trend towards increasing traffic congestion, the outlook suggests that travel conditions will become structurally less reliable over time, but that not all places will be equally affected. But is travel time unreliability a problem? This study uses global positioning systems travel survey data for Chicago to build a regional model of travel time unreliability. The results suggest that unreliability varies spatially during different time periods, but that the average overall network unreliability varies little across times in the day. Using the Chicago Metropolitan Agency for Planning (CMAP)’s 2007 Travel Tracker Survey, a household travel diary survey including both GPS and non-GPS components, we estimate a mode choice model for work trips to explore the influence of unreliability on travel behavior. The results suggest that unreliable auto travel conditions induce mode switching to transit and that the influence is strongest when service by train is already faster than by car. This further suggests that auto travel unreliability may have the strongest influence in metropolitan regions with highly-competitive transit systems. Nevertheless, the influence of travel unreliability is limited and is not the underlying driver of travel decision-making.     

Public responses to policies designed to internalise environmental and social externalities from road transport in New Zealand

Based on a public survey of registered voters, we explore four options for internalising the social and environmental costs of road transport. The options were presented together with generalised factual information about their benefits and costs. Respondents are highly supportive of fuel use efficiency standards and exhaust gas quality standards, with lesser support for proposed initiatives of road user charges and speed reduction. Demographic analysis of responses enables identification of those who might favour or oppose particular options. In this case women are identified as being strongly supportive of the speed reduction option.     

A decision support system for integrated hazardous materials routing and emergency response decisions

Hazardous materials routing constitutes a critical decision in mitigating the associated transportation risk. This paper presents a decision support system for assessing alternative distribution routes in terms of travel time, risk and evacuation implications while coordinating the emergency response deployment decisions with the hazardous materials routes. The proposed system provides the following functionalities: (i) determination of alternative non-dominated hazardous materials distribution routes in terms of cost and risk minimization, (ii) specification of the hazardous materials first-response emergency service units locations in order to achieve timely response to an accident, and (iii) determination of evacuation paths from the impacted area to designated shelters and estimation of the associated evacuation time. The proposed system has been implemented, used and evaluated for assessing alternative hazardous materials routing decisions within the heavily industrialized area of Thriasion Pedion of Attica, Greece. The implementation of the aforementioned functionalities is based on two new integer programming models for the hazardous materials routing and the emergency response units location problems, respectively. A simplified version of the routing model is solved by an existing heuristic algorithm developed by the authors. A new Lagrangean relaxation heuristic algorithm has been developed for solving the emergency response units location problem. The focus of this paper is on the exposition of the proposed decision support system components and functionalities. Special emphasis is placed on the presentation of the two new mathematical models and the new solution method for the location model.