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21.
For a large number of applications conventional methods for estimating an origin destination matrix become too expensive to use. Two models, based on information minimisation and entropy maximisation principles, have been developed by the authors to estimate an O-D matrix from traffic counts. The models assume knowledge of the paths followed by the vehicles over the network. The models then use the traffic counts to estimate the most likely O-D matrix consistent with the link volumes available and any prior information about the trip matrix. Both models can be used to update and improve a previous O-D matrix. An algorithm to find a solution to the model is then described. The models have been tested with artificial data and performed reasonably well. Further research is being carried out to validate the models with real data.  相似文献   
22.
As the interface point between road and rail, intermodal freight terminals (IFTs) are critical elements in the total freight distribution chain. This paper addresses the twin objectives of reducing freight transport costs and improving customer service by putting forward a number of indicators designed to measure the performance of IFTs. Each of the three major performance areas, namely customer service, operational efficiency and terminal productivity are discussed in detail.

A methodology is put forward which enables operating strategies to be evaluated. Computer simulation is used in order to arrive at strategies which reduce operating and capital costs and satisfy customer service requirements. The simulation model outputs include performance measures related to customer service such as mean waiting times required for loading and unloading of containers, as well as productivity measures of terminal operations such as lifting equipment utilisation.  相似文献   
23.
This contribution describes the procedure used during the Prestige oil-spillage event, by means of an Operational Oceanography System, and the behaviour of the present prediction tools (hydrodynamic and dispersion models) applied to it. The accuracy of these tools is estimated by a reanalysis of field data transmitted by a sea surface drifting buoy, released at the time of the oil spill. The numerical models applied were the Regional Ocean Modeling System (ROMS), fed by the available six-hourly NCEP atmospheric information, together with a Lagrangian Particle-Tracking Model (LPTM). ROMS has been used to estimate the current fields for the Bay of Biscay, whilst the LPTM has provided the oil spill trajectories. The results demonstrate that the accuracy of the numerical models depends upon the quality of the meteorological input data. In this case, the current fields at the sea surface, derived by ROMS, have been underestimated by the wind fields of the NCEP reanalysis data. An efficient calibration of these wind fields, with data provided by the Gascony buoy (fixed oceanic and atmospheric station), achieves more realistic looking results; this is reflected in the comparison between the buoy trajectory predicted numerically and the tracked movements of the drifting buoy.  相似文献   
24.
Some European governments subsidize their residents when they travel at sea. This paper seeks to analyze the impact on prices of maritime passengers’ subsidies in Europe. Following a review of the scarce academic literature on this topic and the subsidy scheme in Europe, a sample of firms’ prices and other characteristics of 40 European routes for 2016 are analyzed. Both an estimation of a price equation and a matching approach are applied and reach the same conclusion: prices per kilometer are around 40 per cent higher on those subsidized routes due to subsidies. This outcome reduces the potential subsidy gain to consumers.  相似文献   
25.
In this paper we explore the air pollution levels along types of bicycle facilities using a NO2 land use model previously developed for Montreal. We explore potential associations between bicycle volumes through signalized intersections and pollution levels at those intersections. We further investigate this relationship through the comparison of over thirty cycling corridors as well as an evaluation of the potential exposure of cyclists to air pollution along five routes. We observe NO2 concentrations to be positively correlated with bicycle flows at the intersection level. We also observe that corridors with either a bicycle path or cycle track generally rank higher in terms of bicycle volume and also have higher NO2 concentrations than corridors without bicycle facilities. This indicates that intersections and bicycle facilities with a large number of cyclists are also those characterized with the highest air pollution levels.  相似文献   
26.
This paper addresses the problem of designing safe controllers for vehicle manuevering in Automated Highway Systems (AHS) in which traffic is organized into platoons of closely spaced vehicles. Conditions to achieve safe platooning under normal modes of operation are investigated. The notion of safety is related with the absence of collisions that exceed a given relative velocity threshold. State dependent safety regions for the platoons are designed in such a way that, whenever the state of a platoon is inside these safety regions, it is guaranteed that platoon maneuvering will be safe and follow the behavior prescribed by the finite state machines that control vehicles manuevers. It is shown that it is possible to design control laws that keep the state of the platoons inside these safety regions. The results obtained allow one to decouple the controllers for the regulation of the manuevers and the finite state machines that determine their proper sequence in AHS architectures. The overall complexity of the design and verification of the AHS as an hybrid system is therefore greatly reduced.  相似文献   
27.
The Brazilian ship financing system has some unique features. The funds made available to finance the construction and acquisition of ships are sourced from a tax on import and cabotage freight, payable by the shippers. For Brazilian flagged ships, a portion of the tax generated can be used for the payment of loan instalments. This paper analyses the impact of the tax on the economy as a whole, and discusses the distribution of the tax burden between the shipowner and the shipper, taking into account the maritime transport demand elasticities in Brazil. The paper also analyses the effectiveness of the financing system in reducing the capital cost to shipowner, and the distortion effects produced by the utilization of the tax in loan repayments. The conclusion is that there are important distortions that may threaten the recovery of the maritime industry in Brazil.  相似文献   
28.
Private car ownership plays a vital role in the daily travel decisions of individuals and households. The topic is of great interest to policy makers given the growing focus on global climate change, public health, and sustainable development issues. Not surprisingly, it is one of the most researched transportation topics. The extant literature on car ownership models considers the influence of exogenous variables to remain the same across the entire population. However, it is possible that the influence of exogenous variable effects might vary across the population. To accommodate this potential population heterogeneity in the context of car ownership, the current paper proposes the application of latent class versions of ordered (ordered logit) and unordered response (multinomial logit) models. The models are estimated using the data from Quebec City, Canada. The latent class models offer superior data fit compared to their traditional counterparts while clearly highlighting the presence of segmentation in the population. The validation exercise using the model estimation results further illustrates the strength of these models for examining car ownership decisions. Moreover, the latent class unordered response models perform slightly better than the latent class ordered response models for the metropolitan region examined.  相似文献   
29.
A survey of Bus Rapid Transit BRT and Bus of High Level of Service BHLS around the world indicates that there are about 120 cities with bus corridors, with 99 of the cities entering into the list in the last 12 years. The existing bus corridors comprise about 280 corridors, 4300 km, 6700 stations and use 30,000 buses, serving about 28 million passengers per day. In 2010–2011, 19 cities completed new systems − 16 in the developing world – and seven cities expanded their current systems. By late 2011, about 49 new cities were building systems, 16 cities were expanding their corridors, and 31 cities were in initial planning. This impressive growth may be attributed in part to the successes of Curitiba, Bogotá, México City, Istanbul, Ahmedabad and Guangzhou. These cities show low cost, rapid implementation and high performance BRTs, with significant positive externalities. Interesting trends are emerging, such as the implementation of citywide integrated bus systems, improved processes for private participation in operations, increased funding from national governments, and growth of bus manufacturers and technology providers. Despite the growth, there are some outstanding issues: BRT and BHLS do not have a single meaning and image and are often regarded as a “second best” as compared to rail alternatives. In addition several systems in the developing world suffer problems resulting from poor planning, implementation and operation, due to financial, institutional and regulatory constraints. The BRT and BHLS Industry are in their “infancy” and there is need for consolidation and concerted effort.  相似文献   
30.
The paper presents the main characteristics, costs and impacts of TransMilenio, the bus based mass transit system of Bogotá, using BRT corridors and feeder services. An ex-post cost-benefit analysis is done, including monetary valuation of direct impacts on travel time and travel cost and externalities, such as improved road safety and air quality. Impacts on crime, land values, employment and tax revenue are also presented. The results are positive and robust; nevertheless, it is important to recognize that user perception has declined and there is urgent need to introduce service improvements. The paper also includes an ex-ante evaluation of the projected expansion using current costs, which indicates the need to limit construction capital costs. The results are an indication of the potential of BRT, and the evaluation methodology is applicable to other transit projects.  相似文献   
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