Simulating Demand-responsive Transportation: A Review of Agent-based Approaches

Abstract

In light of the need to make better use of existing transport infrastructure, demand-responsive transportation (DRT) systems are gaining traction internationally. However, many systems fail due to poor implementation, planning, and marketing. Being able to realistically simulate a system to evaluate its viability before implementation is important. This review investigates the application of agent-based simulation for studying DRT. We identify that existing simulations are strongly focused on the optimisation of trips, usually in favour of the operator, and rarely consider individual preferences and needs. Agent-based simulations, however, permit incorporation of the latter, as well as capture the interactions between operators and customers. Several areas of future research are identified in order to unify future research efforts.     

How big data enriches maritime research – a critical review of Automatic Identification System (AIS) data applications

ABSTRACT

The information-rich vessel movement data provided by the Automatic Identification System (AIS) has gained much popularity over the past decade, during which the employment of satellite-based receivers has enabled wide coverage and improved data quality. The application of AIS data has developed from simply navigation-oriented research to now include trade flow estimation, emission accounting, and vessel performance monitoring. The AIS now provides high frequency, real-time positioning and sailing patterns for almost the whole world's commercial fleet, and therefore, in combination with supplementary databases and analyses, AIS data has arguably kickstarted the era of digitisation in the shipping industry. In this study, we conduct a comprehensive review of the literature regarding AIS applications by dividing it into three development stages, namely, basic application, extended application, and advanced application. Each stage contains two to three application fields, and in total we identified seven application fields, including (1) AIS data mining, (2) navigation safety, (3) ship behaviour analysis, (4) environmental evaluation, (5) trade analysis, (6) ship and port performance, and (7) Arctic shipping. We found that the original application of AIS data to navigation safety has, with the improvement of data accessibility, evolved into diverse applications in various directions. Moreover, we summarised the major methodologies in the literature into four categories, these being (1) data processing and mining, (2) index measurement, (3) causality analysis, and (4) operational research. Undoubtedly, the applications of AIS data will be further expanded in the foreseeable future. This will not only provide a more comprehensive understanding of voyage performance and allow researchers to examine shipping market dynamics from the micro level, but also the abundance of AIS data may also open up the rather opaque aspect of how shipping companies release information to external authorities, including the International Maritime Organization, port states, scientists and researchers. It is expected that more multi-disciplinary AIS studies will emerge in the coming years. We believe that this study will shed further light on the future development of AIS studies.     

The mispricing of transportation initial public offerings in the Chinese mainland and Hong Kong

The main objective of this study is to determine the level of mispricing of transportation IPOs in the Chinese mainland and Hong Kong. A subsidiary objective is to test the hypothesis that there is a strong positive correlation between the initial day returns that are required for new equity issues and the level of ex ante uncertainty associated with the IPO. By applying a standard methodology in finance for assessing the existence and scale of mispricing, the study finds significant underpricing for transportation IPOs in the Chinese mainland and Hong Kong. There is also evidence that freight-related IPOs are subject to more severe underpricing than non-freight related IPOs, and that water-transport IPOs are underpriced more than IPOs of other types of transport business. It is concluded that there does exist support for the hypothesis that the level of ex ante uncertainty is strongly associated with the level of mispricing and that this explains cross-sectional differences in the degree of underpricing of IPOs. In this respect, the results from the Chinese mainland and Hong Kong are consistent with the results of similar studies conducted elsewhere.     

Technical Note: Force Control in Electrohydraulic Active Suspensions Revisited

The inner loop control for the actuator force can be quite simply compensated by means of a correction term to the desired force signal at the input. The correction requires only a measurement of the actuator piston velocity and is employed to cancel the loop disturbance caused by the oil flow to the actuator. Although an additional time constant is introduced by the integration in the inner loop force control, the overall performance is nevertheless quite close to that of an ideal optimal system.     

Technical Note: RMS Values for Control Force, Suspension Stroke and Tyre Deflection in an Active Suspension

Expressions are derived for the numerical computation of rms values for control force, suspension stroke and dynamic tyre deflection in a quarter-car vehicle model on a random road of given roughness. A quadratic performance index is employed and the effects of the assumed weighting factors on the rms values and overall static stiffness determined.     

Influence of local government on port investment: implications of China’s decentralized port governance system

ABSTRACT

The pursuit of better performance by the local government can influence the investment decision-making related to port expansion. This paper compares the ceilings at which the port enterprise and the local government would stop making investments. To achieve this, the benefits to the port enterprise and the local government are measured over a given time period. An empirical study investigating how a port would respond if a rival port uses a type of capacity investment strategy is conducted for two major ports in Liaoning. The time at which the local government and the port enterprise would stop making investments and the final equilibrium are developed using the data from 2010. From the empirical results, it was found that investment in port capacity contributes greatly to the local government’s performance. Meanwhile, different investment ceilings are discovered for the port enterprise and the local government. This research is meaningful for discussing the institutional relationship between the local government and the port enterprise in China’s current decentralized port governance system.

This paper is a revised and expanded version of a paper entitled ‘Port expansion mechanism in the context of political achievement of local government: a special phenomenon in China’ presented at International Association of Maritime Economists 2012 Taipei Conference during 5th September –8th September.     

Assessing the long term benefit of banning the use of hand-held wireless devices while driving

An increasing number of legislative efforts have been undertaken to prohibit the use of hand-held wireless devices while driving. As of July 2012, ten states and the District of Columbia enforce laws banning the use of hand-held cell phones while driving. Thirty-nine states and the District of Columbia have banned text messaging while driving. Recent studies of driver behavior suggest that hand-held wireless device usage negatively impacts driver performance. However few studies at the aggregate level address the plausible link between the use of hand-held wireless devices while driving, increased risk of automobile accidents, and government legislative efforts to reduce such risk. This paper analyzes data at the aggregate level and builds a regression model to estimate the long term accident rate reduction due to a hand-held ban. This model differs from previous studies, which consider short term accident rate reduction, by considering time trends in the accident rate due to the ban. Additionally, counties considered in this analysis are placed into groups based on driver density, defined by the number of licensed drivers per centerline mile of roadway, and a separate analysis is performed within these groups. This approach allows one to better quantify the effect of hand-held bans in counties of different driver densities. Results from this paper suggest that bans on hand-held wireless device use while driving reduce the rate of personal injury accidents in counties with high levels of driver density, but may increase accident rates in counties with low driver density levels. These results can inform transportation policymakers interested in reducing automobile-accident-risk attributable to the use of hand-held wireless devices while driving.     

Cutting vehicle emissions with regenerative braking

This paper presents an analysis of vehicle regenerative braking systems as a quick and relatively easy means of achieving higher overall fuel efficiency and lowering carbon emissions. The system involves the installation of an additional electric motor/generator in parallel to the vehicle’s internal combustion engine and is used in conjunction with a DCDC converter and ultracapacitor. The system is used to recapture the energy lost in vehicle braking, significantly reducing a vehicle’s overall energy consumption and lowering vehicle emissions. Experimentally-based evidence is collected and compared for two sample vehicles to deduce the potential fuel and emissions saving.     

本土汽车生产商面临挑战

在本届上海车展上,中国本土汽车生产商占据了4个展厅,全面展示了其在技术和研发方面的最新进展。为了应对日趋激烈的市场竞争和行业合并需求的增长,本土汽车生产商若想保持现在的市场份额,必将迎接更大的考验。