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A new procedure for generating optimal transport strategies has been applied in nine European cities. A public sector objective
function which reflects concerns over efficiency, environmental impact, finance and sustainability is specified and a set
of policy measures with acceptable ranges on each, identified. Optimal strategies based on combinations of these policy measures
which generate the optimal value of the objective function, are identified, and compared between cities. Resulting policy
recommendations are presented. The results demonstrate the importance of an integrated approach to transport strategy formulation.
They emphasise the role of changes in public transport service levels and of fares, and of charges for car use. By contrast,
new infrastructure projects are less frequently justified. In the majority of cities the revenues from car use charges are
sufficient to finance other elements in the strategy. However, private sector involvement either in initial financing or in
operation may be desirable. Revised objective functions to reflect private sector involvement are specified, and optimal strategies
with private sector operation of public transport are also identified. The requirement to meet private sector rates of return
for public transport operation typically results in lower frequencies and higher fares; charges for car use then need to be
raised to satisfy public policy objectives, but system performance is reduced.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
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W.Bruce Allen Mohamed M. Mahmoud Douglas McNeil 《Transportation Research Part B: Methodological》1985,19(5):447-456
Reliability of transit time is reputed to be the most important variable influencing freight transport today, according to shipper surveys. Average transit time also plays a major role. A model is developed that shows how a cost-minimizing shipper will adjust its economic order quantity as reliability and/or time in transit changes. Such changes impact on average inventory costs, ordering costs, expected shortage costs and expected excess costs. The model is developed for both discrete and continuous transit time distributions. Reliability is defined as the variance of transit time. A matrix is prepared for some sample data, which shows the minimum cost attainable with each mean/variance of transit time distribution. Comparing across rows and columns of the matrix enables one to show the value (reduction in total cost) obtainable by improving reliability and/or mean transit time. In addition, value can be obtained by improving reliability while increasing average transit time. It is suggested that the model can be used for shippers in negotiating service improvements with carriers and by carriers in negotiating service improvements with shippers. In the former case, the carrier can determine how much they are willing to pay for the improvement, whereas in the latter case, the carriers can determine how much they are able to charge for the improvement. 相似文献
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Bao-min Liu Xiao-lin Niu Ben-yu Jiang Mike Saddon Karen McNeil Philip Chowienczyk 《西安交通大学学报(英文版)》2009,21(2):114-119
Objective To determine whether reduction In central pressure augmentation and central systolic blood pressure by nitroglycerine (NTG) results from effects on pre-lead or is due to arterial dilation. Methods We compared effects of NTG with these of lower body negative pressure (LBNP). Hemodyunmic measurements were made at rest, during LBNP (10, 20 and 30 mmHg, each for 15 min) and after NTG (10, 30 and 100μg/min, each dose for 15 min) in ten healthy volunteers. Cardiac pre-lead, stroke volume and cardiac output were assessed by echacardiography. Central pressure an mnentation and central systolic pressure were obtained by radial tonometry using a transfer function. Results LBNP (20 mmHg) and NTG (30μg/min) reduced pre-lead (as measured by the peak velocity of the S wave in the superior vena eava) to a similar degree [by (26. 8 ± 3.8) % and (23.9 ± 3. 4) %, respectively]. Compared to LBNP, NTG reduced systemic vascular resistance [by (32. 9 ± 7.5) %, p< 0. 01], decreased peripheral and central pressure augmentation [by (20. 8 ± 3. 4)% units and (12. 9±2. 9)% units, respectively, each P< 0. 01]. Conclusion These results suggest that a reduction in pre-load does not explain reduction in pressure augmentation and central systolic blood pressure by NTG and that these effects are mediated through arterial dilation. 相似文献
54.
Abstract This article investigates the role of bus rapid transit as a tool for mitigation of transport‐related carbon dioxide (CO2) emissions. We analyse a Quality Bus Corridor (QBC) implemented in Dublin, Ireland, in 1999 and estimate CO2 emissions associated with differing levels of bus priority for the period 1998–2003 and for the Kyoto commitment period (2008–12). Associated monetary values are established using CO2 prices from the European Union Emissions Trading Scheme. We find that, in the absence of a QBC, peak‐time emissions for our sample population would have been 50% higher than in the factual scenario. For the Kyoto commitment period, we find the median value of the policy implementation to be in the region of [euro]650 000. 相似文献
55.