共查询到16条相似文献,搜索用时 15 毫秒
1.
Container barging has gained in importance in port-related transport along with the need for sustainable transport. Nevertheless, coordination problems between terminal operator and barge operator exist, and performance lags behind. This paper analyses factors that may hinder or stimulate a better future performance of container barging in the port of Rotterdam. A case study is accomplished and guided by a framework rooted in Institutional Economics. Despite favourable conditions set by governments and the port authority, the share of container barging has hardly grown. The container barging sector in Rotterdam is embedded in a history with many alliances, a high degree of organisation, and a good track record in the development of institutional arrangements to solve coordination problems. However, the present contractual relations in the transport chain form an inadequate condition. From a theoretical perspective, the paper shows the value of studying port-related transport chains by acknowledging their institutional context. 相似文献
2.
Berth allocation is essential for efficient terminal utilization in container ports, especially those in Asia. This paper is concerned with a berth allocation problem(BAP) that minimizes the sum of port staying times of ships and that minimizes dissatisfaction of the ships in terms of the berthing order. In general there exist tradeoffs between these objectives. An algorithm is presented to identify noninferior solutions to the BAP. The algorithm is demonstrated with some sample problems and the results indicate the importance of the problem in efficient terminal utilization. 相似文献
3.
The control of automated container terminals is complex since Quay Cranes (QCs), Automated Guided Vehicles (AGVs) and Automated Stacking Cranes (ASCs) interact intensively for transporting containers, while collision avoidance of equipment must be ensured. This paper proposes a methodology to generate collision-free trajectories of free-ranging AGVs in automated container terminals, while minimizing the makespan of the whole container handling system. A hierarchical control architecture is proposed to integrate the scheduling of interacting machines and trajectory planning of AGVs. Following a so-called overall graph sequence by a scheduler, the collision-free trajectories of AGVs are determined by solving a collection of mixed integer linear programming problems sequentially. Simulation results illustrate the potential of the proposed methodology. 相似文献
4.
《Transportation Research Part A: Policy and Practice》2002,36(8):743-762
This paper applies a `port function matrix' to analyse the administrative and ownership structures of major container ports in Asia. The relative efficiency of these ports is then assessed using the cross-sectional and panel data versions of the `stochastic frontier model'. The estimated efficiency measures are broadly similar for the two versions of the model tested. From the results of the analysis, it is concluded that the size of a port or terminal is closely correlated with its efficiency and that some support exists for the claim that the transformation of ownership from public to private sector improves economic efficiency. While this provides some justification for the many programmes in Asian ports which aim to attract private capital into both existing and new facilities, it is also concluded that the level of market deregulation is an important intervening variable which may also exert a positive influence. 相似文献
5.
AbstractThe European railway market has gone through a period of liberalization over the last two decades. The liberalization of the railway market has also affected port-related railway transport. Efficient port-related transport chains are key in the competition among ports, however providing this efficiency is to a large extent a coordination challenge. Many forms of coordination are needed to ensure that the railway chain operates efficiently, including the bundling of cargo, and good organization between railway companies, terminal operators and the infrastructure managers to realize an efficient use of assets. From the literature, it appears that less attention has been paid to the economic organization of port-related railway transport in general, and specifically in the new liberalized institutional environment. The goal of this paper is to come up with a framework to better understand the issue of coordination in port-related railway chains in a liberalized institutional environment. This paper presents a conceptual framework rooted in Transaction Cost Economics (TCE). Based on an in-depth study into coordination in liberalized container railway market at the Port of Rotterdam, empirical illustrations are used to adjust the TCE approach toward a dynamic model influenced by Douglas North's theory on economic and institutional change. Empirics from the port of Rotterdam show that new players have entered the railway market and their role has changed. This paper shows that coordination of railway operations has become more complex after the regime change. From a port perspective, liberalization does not lead to an optimal allocation of resources in a process that is highly operationally interdependent. In the liberalized environment, coordination arrangements are necessary to enable efficient coordination of railway operations in Rotterdam. 相似文献
6.
The fact that electric vehicles (EVs) are characterized by relatively short driving range not only signifies the importance of routing applications to compute energy efficient or optimal paths, but also underlines the necessity for realistic simulation models to estimate the energy consumption of EVs. To this end, the present paper introduces an accurate yet computationally efficient energy consumption model for EVs, based on generic high-level specifications and technical characteristics. The proposed model employs a dynamic approach to simulate the energy recuperation capability of the EV and takes into account motor overload conditions to represent the vehicle performance over highly demanding route sections. To validate the simulation model developed in this work, its output over nine typical driving cycles is compared to that of the Future Automotive Systems Technology Simulator (FASTSim), which is a simulation tool tested on the basis of real-world data from existing vehicles. The validation results show that the mean absolute error (MAE) of cumulative energy consumption is less than 45 W h on average, while the computation time to perform each driving cycle is of the order of tens of milliseconds, indicating that the developed model strikes a reasonable balance between efficacy of representation and computational efficiency. Comprehensive simulation results are presented in order to exemplify the key features of the model and analyze its output under specific highly aggressive driving cycles for road gradients ranging from −6% to 6%, in support of its usability as a practical solution for estimating the energy consumption in EV routing applications. 相似文献
7.
This paper is concerned with the problem of designing a decentralized consensus protocol for platooning of non-identical vehicles in the presence of heterogeneous time-varying communication delays. The proposed control protocol makes use of a state feedback and to this aim drivetrain dynamics are modeled as third-order linear systems. Necessary and sufficient conditions for convergence and exponential stability, derived by using an appropriate Krasovskii functional, demonstrate the ability of the platoon in reaching the required regime with an exponentially bounded behavior. The proposed LMI-based approach allows to estimate both delay margin and decay rate. Moreover, convergence is proven under switching communication network topologies by means of a Lyapunov-Razumikhin function, and the assessment of a string stable behavior has been also theoretically investigated. High-fidelity simulations with Plexe show the effectiveness of the theoretical results in different driving conditions and in the presence of external disturbances and communication impairment. Different communication channel models are used in the validation stage to further prove robustness of the proposed methodology with respect hard delay and packets losses. 相似文献
8.
V. Kreibich 《Transportation》1978,7(2):137-145
The development of the Munich Rapid Transit System, coupled with the growth of the Munich region, has had a major effect on the spatial structure of the region. The radial form of the rapid transit system has led to an outward movement of higher income families and a strengthening of the service function of the city centre, to the cost of local centres. Lower income families are tending to settle in the city centre fringe areas, although their primary employment opportunities, in manufacturing industry, are increasingly moving to the urban fringe. There is, thus, a growing spatial separation between homes and workplaces and although the rapid transit system has reduced traffic congestion in Munich, it has encouraged the development of an urban structure which is not compatible with the objectives of either the state or the region. 相似文献
9.
《Transportation Research Part A: General》1980,14(1):70
10.
Various regulations are imposed on shipping to increase energy efficiency and reduce environmental impacts. Alternative fuels and power systems are among the solutions for compliance with these regulations. The power system of a ship may not operate optimally because of the diversity of the operational profile during its lifetime. This article uses an activity-based approach and big data from the Automatic Identification System (AIS) to study the operational profiles of eight ship types operating in Norwegian waters around mainland Norway in 2016. The aim is to identify ship types that can benefit from electric and hybrid propulsion through analysis of their operational profiles. Close to shore, the operational profiles of various ship types are similar, and all ships spend a great proportion of their time with lower loads. As the distance from shore increases, the operational profiles of various ship types follow distinct trends. Among the considered ship types, reefers spend more operational time close to the diesel engine design condition. On the other hand, offshore and passenger ships show the most dynamic operational profiles and spend a large percentage of their operational time with a partial load, away from diesel engine design conditions. Such ships can benefit from hybridisation, diesel-electric propulsion, and other electric concepts, such as batteries and fuel cells. Another option is to downsize diesel engines for better operation while fuel cells and batteries supply peak and partial loads. Operational profiles are plotted and details of the approach are presented in the article. 相似文献
11.
Karel Martens Aaron Golub Glenn Robinson 《Transportation Research Part A: Policy and Practice》2012,46(4):684-695
Transportation improvements inevitably lead to an uneven distribution of user benefits, in space and by network type (private and public transport). This paper makes a moral argument for what would be a fair distribution of these benefits. The argument follows Walzer’s “Spheres of Justice” approach to define the benefits of transportation, access, as a sphere deserving a separate, non-market driven, distribution. That distribution, we propose, is one where the maximum gap between the lowest and highest accessibility, both by mode and in space, should be limited, while attempting to maximize average access. We then review transportation planning practice for a priori distributional goals and find little explicit guidance in conventional and even justice-oriented transportation planning and analyses. We end with a discussion of the implications for practice. 相似文献
12.
《Transportation Research Part A: General》1990,24(3):211-215
A method of estimating the effect of sampling error on derived results is described. The technique involves the division of the full sample into overlapping subsamples and the subsequent parallel processing of these subsamples. The particular advantage of the technique is the way in which it can be used to follow automatically the effect of sampling variance through the most complex operations, such as the calibration of a transport model. 相似文献
13.
14.
This paper applies a novel adaptive approach consisting of Artificial Neural Network (ANN) and Fuzzy Linear Regression (FLR) to improve car ownership forecasting in complex, ambiguous, and uncertain environments. This integrated approach is applied to forecast car ownership in Iran from 1930 to 2007. In this study, the level of car ownership is viewed as the result of demographic, politico-social, and urban structure factors including average family size, total population density, urban population density, urbanization rate, gross national product per capita, gasoline price, and total road length. To capture the potential complexity, uncertainty, and linearity relation between the car ownership function and its determinants, ANN and FLR (including eight well-known FLR) approaches are applied to the collected data. Next, the preferred ANN is selected based on sensitivity analysis results for the test data while the preferred FLR is identified with regard to ANOVA and MAPE results. The results obtained from the performance comparison demonstrate the considerable superiority of the preferred ANN over the preferred FLR regarding the nonlinear and complex nature of the car ownership function in Iran. This is the first study that presents an ANN-FLR approach for car ownership forecasting capable of handling complexity and non-linearity, uncertainty, pre-processing, and post-processing. 相似文献
15.
《Transportation Research Part A: General》1981,15(4):345