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71.
    
Over the last two decades, infrastructure development has often been supported by public–private partnerships, particularly under concession arrangements. This paper addresses terminal concession contracts in the seaport sector, and especially the problem of risk-sharing. An effective allocation of risks is the base for the well functioning of the market, and for the success of the ‘landlord’ model. Under this model, the relationship between concessionaires and port authorities is fully dependent on a contract that should be in force for the period of the concession (20, 30 or more years). Based on several Portuguese concession contracts, this paper addresses the issue of risk-sharing agreements. Some policy implications are drawn, namely, alternative contract arrangements to decrease opportunistic behaviour by concessionaires, and to provide incentives to improve efficiency.  相似文献   
72.
  总被引:1,自引:0,他引:1  
This paper presents a linear programming model designed to determine the optimum fuel loading quantities along a route network for a Brazilian domestic airline. Assuming that there are no volume purchase or storage capacity restrictions on each station, the analysis is carried out for one aircraft on one day of its schedule. Results are extrapolated for a monthly and yearly basis. Through the proposed model, it is seen that such a fuel tankering technique leads to a 5% economical saving, but produces a 1% additional fuel burn. A discussion on the environmental impact for this procedure is also proposed. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   
73.
    
Abstract

This paper analyses the productivity of a representative sample of African seaports from 2002 to 2008. Productivity scores are decomposed, based on the Luenberger productivity indicator, and the nature of technological change is analysed. The paper finds that Nigerian seaports are the most efficient, followed by Angola and Mozambique. Discussions of the results as well as related policy implications are provided.  相似文献   
74.
Schedule-based or headway-based control schemes to reduce bus bunching are not resilient because they cannot prevent buses from losing ground to the buses they follow when disruptions increase the gaps separating them beyond a critical value. (Following buses are then overwhelmed with passengers and cannot process their work quick enough to catch up.) This critical gap problem can be avoided, however, if buses at the leading end of such gaps are given information to cooperate with the ones behind by slowing down.This paper builds on this idea. It proposes an adaptive control scheme that adjusts a bus cruising speed in real-time based on both, its front and rear spacings much as if successive bus pairs were connected by springs. The scheme is shown to yield regular headways with faster bus travel than existing control methods. Its simple and decentralized logic automatically compensates for traffic disruptions and inaccurate bus driver actions. Its hardware and data requirements are minimal.  相似文献   
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为了制定引导公众意识与行为转变的策略,尤其是对无车日的规划以及为将其应用于其他可持续性城市交通措施中提供指南.介绍了几种有关引导公众对于公共交通与其他可持续性交通方式的意识与行为转变的策略,重点介绍了公众目前与将来可以使用的可持续性交通方式,以及公众尤其是决策者对于城市交通问题的态度及其对于可持续性交通解决方案(如步行、骑自行车与使用公共交通工具等)的看法.最后,提出媒体是提高公众对于可持续性交通活动意识的有效渠道.  相似文献   
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78.
An approach is presented to assess the reliability of ship hulls made of composite materials under sagging moments. Buckling, first-ply failure, and ultimate collapse are regarded as the three possible failure modes of ship hulls of composite materials under sagging moments. Reliability estimates were carried out by a combination of the first-order second-moment method and the response surface methodology. A ship hull of composite materials under sagging moments was evaluated and the results showed that the effects on reliability estimates of the model uncertainty in the longitudinal strength of the ship hull, the model uncertainty of the sagging moments, and the sagging moments were significant, whereas the influences of the stochastic characteristics of material elastic moduli were relatively unimportant.  相似文献   
79.
Transportation - This paper presents a systematic way of understanding and modeling traveler behavior in response to on-demand mobility services. We explicitly consider the sequential and yet...  相似文献   
80.
Industrialized countries have extensive experience with various transportation energy conservation measures and have been making steady progress in improving the efficiency of their transport sector. Less Developed Countries (LDCs) have also been making progress, but their experience in many aspects of transportation energy conservation is very limited. Development organizations have funded many transportation projects in developing countries, but the vast majority of these projects were designed to improve the transportation infrastructure. Very few transportation energy conservation projects have been implemented and decision-makers face a scarcity of information on effective strategies. This paper gives an overview of transportation projects in LDCs in order to identify those transportation energy conservation measures that offer the greatest potential for LDCs. Two case studies, from Tunisia and Costa Rica, are given to illustrate the issues involved in implementing transportation energy conservation measures in LDCs. Conclusions are drawn to suggest actions for developing countries and for development organizations.Acronyms DECAT Driver Energy Conservation Awareness Training - DSE Direccion Sectorial de Energia (Costa Rica) - GDP Gross domestic product - km Kilometer - LDCs Less Developed Countries - TOE Metric tonne of oil equivalent - USAID US Agency for International Development  相似文献   
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