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761.
762.
A. Facchinetti L. Gasparetto 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2013,51(4):499-516
Hardware-in-the-loop (HIL) simulation is a promising technique to study the pantograph–catenary interaction problems by realising the interaction of a physical pantograph with a mathematical model of the overhead equipment (catenary). However, the computing power presently available on real-time CPUs only allows to run simplified models of the overhead equipment. Therefore, it is important to define catenary models that are suitable for real-time simulation and at the same time capable of accurately representing the dynamic behaviour of the catenary. In this paper, the use of a catenary model based on modal superposition is considered, and the effect of changing the number of modelled spans and the number of modal components allocated to the contact and messenger wires is investigated in view of finding the best model compatible with real-time simulation. Comparisons between HIL simulation results and line measurements are presented, to quantify the accuracy of the hybrid simulation method developed. 相似文献
763.
The first field experiment with intelligent speed adaptation (ISA) in Malaysia was held in December 2010 in the State of Penang. Eleven private cars were instrumented with an advisory system. The system used in the present study included a vocal warning message and a visual text message that is activated when the driver attempts to exceed the speed limit. When the driver decreases the speed, the warning stops; otherwise it is continuously repeated. The test drivers drove the vehicles for three months with the installed system, and the speed was continuously logged in all vehicles. The warning was however only activated in the second month of the three month period. The present study aimed to evaluate the effects of an advisory ISA on driving speed, traffic safety, and drivers' attitude, behavior, and acceptance of the system. To examine these effects, both the survey and the logged speed data were analyzed and explored. The results show a significant reduction in the mean, maximum and 85th percentile speed due to the use of the system. However, there was no long-lasting effect on the speed when the system was deactivated. In the post-trial survey, drivers declared that the system helped them well in following the speed limits and that it assisted them in driving more comfortably. Furthermore, the warning method was more accepted compared to a supportive system, such as active accelerator pedal (AAP). After the trial, most drivers were willing to keep an ISA system. 相似文献
764.
This workshop discussed challenges of measuring the performance of transport contracts, which is usually achieved by benchmarking the relevant services against a few key performance indicators (KPIs). Such KPIs (the workshop identified cost efficiency, service quality and safety/security as the top three) can be explicitly included in the contracts (with a focus on compliance) or can be rather informal and part of a trusting partnership. Limited availability of good data and appropriate information technology systems appear to be the greatest challenges within developed markets. In the context of creating a formal market (such as the South African taxi market), which encourages public transport measurement and compliance, our findings suggest that it is important to set as a first step minimum standards to address the backlog with respect to establishing performance measurement regimes. 相似文献
765.
Jan A. Berg-Andereassen 《Maritime Policy and Management》2013,40(4):381-395
This paper tests two fundamental hypotheses concerning international maritime statistics. The first one deals with the question of stationary of the maritime market statistics. The second hypothesis tested is the assumption that the international maritime statistical time series are not distributed according to a normal of Guassian probability law, but rather belong to the same family of distributions with distinctly different critical parameters. Through well documented statistical methods, the paper concludes that the international freight rates observed on a day to day basis are generated by a random walk process. The paper finds that the shipping industry's conventioal wisdom is essentially correct. ‘Last done’ is as good a forecast of tomorrow's freight rate as any other generated by more sophisticated forecasting methods. Furthermore, freight rates and secondhand tonnage prices fluctuate closely together. The freight rates are generated by stochastic processes fully described by the Paretian family of distributions. The critical parameters of these distribution, the characteristic exponents, are such that the risk conscious ship operator can indeed reduce his exposure to risk by securing a correct set of freight rate contracts. 相似文献
766.
Travel time variability (i.e., random variations in travel time) leads to a travel time distribution for a repeated trip from a fixed origin to destination (e.g., from home to work). To represent travel time variability, a series of possible travel times per alternative (departure time, route or mode) are often used in stated choice experiments. In the traditional models, the probabilities associated with different travel scenarios (e.g., arriving early, on time and late) shown in the experiments are directly used as weights. However, evidence from psychology suggests that the shown probabilities may be transformed (underweighted or overweighted) by respondents. To account for this transformation of probabilities, this study incorporates perceptual conditioning through a non-linear probability weighting function into a utility maximisation framework, within which the empirical estimate of the value of expected travel time savings is estimated. The key advantage of this framework is that the estimated willingness to pay value can be directly linked to the source of utility (i.e., the probability distribution of travel time), while taking into account the perceptual transformation of probabilities. 相似文献
767.
The emergence of Intelligent Transport Systems (ITS) has been recognised with many initiatives during the last 20 years. In Europe, the “ITS Action Plan” identifies a number of applications as key elements contributing to the efficient co-ordination of the overall transport chain. The context and experience surrounding the recent widespread development of technological tools and ICT platforms to support the emergence of ITS are notable for the way in which they permeate the transport and logistics chain. But a key question remains: to what extent is the public transport sector able to exploit the wider benefits of ITS? 相似文献
768.
Lynne Zeitlin Hale Mark Amaral Abdulrahman S. Issa B. A. J. Mwandotto 《Coastal management》2013,41(1):75-85
Site-based projects were initiated in Chawka Bay-Paje, Zanzibar, and Nyali-Bamburi-Shanzu, Kenya, to demonstrate the benefits of an integrated coastal management (ICM) approach for addressing coastal issues such as tourism development and enhancement of resource-dependent village economies in eastern Africa. A two-year, multidonor project used three primary strategies to make rapid, but sustainable, progress toward ICM. These included using interagency government teams for ICM planning, adopting an internationally recognized framework for ICM as a project ''road map,'' and explicitly incorporating capacity-building strategies into all aspects of the project. Within two years, integrated ICM action strategies, prepared through participatory processes, were being implemented at both sites, and both teams were working to expand the scale and scope of ICM in their nation. More importantly, the project helped create committed, capable, interagency groups that continue to work together to address urgent ICM issues. 相似文献
769.
E. G. Coombes A. P. Jones I. J. Bateman J. A. Tratalos J. A. Gill D. A. Showler 《Coastal management》2013,41(1):94-115
As tourists are sensitive to weather conditions and changes to the environments they visit, it is likely that climate change will affect coastal recreation in the future. To understand these impacts, it is first important to quantify how visitor numbers are associated with beach characteristics and weather patterns. Using the East Anglian coastline, UK, as a case study, information on the spatial distribution of visitors recorded from aircraft flights is combined with beach characteristic data in a Geographical Information System. In addition, surveys are undertaken at two beaches to assess temporal variations in visitation. The study finds a diverse range of characteristics are associated with visitor numbers. These findings are evaluated alongside the anticipated effects of climate change and management policies. Although it is predicted that warmer weather will increase visitor numbers overall, sea-level rise may reduce numbers at wide sandy beaches, which are currently most preferred by tourists. 相似文献
770.
Leslie I. Ward-Geiger Gregory K. Silber René D. Baumstark Tanya L. Pulfer 《Coastal management》2013,41(3):263-278
Collisions with ships are a significant threat to the endangered North Atlantic right whale. To reduce this threat, The National Oceanic and Atmospheric Administration's (NOAA) National Marine Fisheries Service (NMFS) and the U.S. Coast Guard (USCG) established the Mandatory Ship Reporting System (MSRS) in July 1999. Under this system, all commercial ships, 300 gross tons or greater, are required to report to a shore-based station when entering either of two areas surrounding designated critical habitat: one in waters off the northeastern United States and the other off the southeastern United States. Information reported to the system includes entry location, destination, intended route, and speed. Reporting ships receive an automated message indicating precautionary steps to be taken to avoid hitting whales. Ship tracks between sequential ship locations were estimated by using a geographic information system (GIS) and mapped to illustrate traffic patterns within the MSRS. In the northeast, 69% of all valid tracks transited right whale critical habitat areas. All but two southeastern tracks intersected critical habitat. “High-use” traffic corridors were identified within the system. The majority of ships (59%) traveled at speeds greater or equal to 14 kn, a reported speed at which large whales may be critically injured. This characterization provides a portrait of ship traffic in right whale aggregation areas that can be used to develop measures to reduce the threat of ship strikes to right whales. 相似文献