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81.
Restoration of nearshore ecosystems presents many challenges for stakeholder involvement. Using surveys and interviews we examined stakeholder values, preferences, and potential coalitions surrounding nearshore restoration in the Whidbey sub-basin of Puget Sound. Most stakeholders in our study believe that Puget Sound nearshore problems are severe and urgent, and that it is worth investing in restoration. They do not agree on the causes of nearshore degradation, yet support stronger regulatory enforcement and increased public ownership as possible solutions to nearshore problems. Five potential stakeholder coalitions were identified based on shared values. These values reflect a varied spectrum of support for public sector solutions to nearshore problems and were labeled: No Government Intervention, Property Rights, Private Land Stewardship, Protect Undeveloped Areas, and Large Scale Restoration. The potential coalitions identified confirm the Advocacy Coalition Framework hypothesis that coalition members who share values do not necessarily share stakeholder demographics or preferences. This study demonstrates one method for understanding local stakeholders, and will help managers direct project resources, planning, and management, through reliance on both stakeholder and scientific input. In addition, managers can use information about stakeholder values and potential coalitions to more effectively frame communication products and stakeholder involvement activities. 相似文献
82.
Phuong Nguyen-Hoang Ryan Yeung 《Transportation Research Part A: Policy and Practice》2010,44(10):841-853
Paratransit is a flexible demand-responsive form of public transportation intended for transporting mobility impaired individuals. This is the first study that estimates both demand and cost functions for publicly provided paratransit in the United States and the first to conduct a benefit-cost analysis for this mode. We find that the benefits of paratransit far exceed its associated costs. The results suggest that paratransit riders have few transportation alternatives available to them. We also find that the level of service matters in the demand for paratransit. 相似文献
83.
Robert U. Ayres 《运输规划与技术》2013,36(2):107-113
This paper is addressed to the question of social costs and social benefits (primarily environmental) which might derive from a large‐scale substitution of so‐called mass‐transit for the present, largely private, system of automotive transportation. Energy consumption and emissions are compared for the two basic alternatives and several variants. Varying degrees of physiological tolerance to pollutants are taken into account, in an attempt to develop comparable weight‐factors for different types of emissions. It is suggested that if automobiles succeed in meeting the 1975/76 emission standards set by the Clean Air Act of 1970, rail rapid transit will probably offer no advantage (in environmental terms) unless electric power is available from virtually non‐polluting sources (e.g., natural gas or nuclear plants). Economic implications of large‐scale substitution are examined, and it is noted that such substitution would involve major restructuring of our society as a whole. However, more intensive use of mass transit in central cities, possibly in conjunction with various measures to discourage the use of private automobiles in very congested areas is feasible and likely. 相似文献
84.
Sheldon H. Jacobson Douglas M. King Kevin C. Ryan Matthew J. Robbins 《Transportation Research Part A: Policy and Practice》2012,46(10):1586-1593
An increasing number of legislative efforts have been undertaken to prohibit the use of hand-held wireless devices while driving. As of July 2012, ten states and the District of Columbia enforce laws banning the use of hand-held cell phones while driving. Thirty-nine states and the District of Columbia have banned text messaging while driving. Recent studies of driver behavior suggest that hand-held wireless device usage negatively impacts driver performance. However few studies at the aggregate level address the plausible link between the use of hand-held wireless devices while driving, increased risk of automobile accidents, and government legislative efforts to reduce such risk. This paper analyzes data at the aggregate level and builds a regression model to estimate the long term accident rate reduction due to a hand-held ban. This model differs from previous studies, which consider short term accident rate reduction, by considering time trends in the accident rate due to the ban. Additionally, counties considered in this analysis are placed into groups based on driver density, defined by the number of licensed drivers per centerline mile of roadway, and a separate analysis is performed within these groups. This approach allows one to better quantify the effect of hand-held bans in counties of different driver densities. Results from this paper suggest that bans on hand-held wireless device use while driving reduce the rate of personal injury accidents in counties with high levels of driver density, but may increase accident rates in counties with low driver density levels. These results can inform transportation policymakers interested in reducing automobile-accident-risk attributable to the use of hand-held wireless devices while driving. 相似文献
85.
86.
This study investigates the compression property experiment to examine impact absorption when aluminum foam is applied to crash box in order to absorb impact energy in car crash with low speed. The result of compression property experiment shows that case 6, which involves the buckling that collapses into 5-layer structure, is the best model with regard to impact absorption. This study analyzes impact characteristics according to the structure of crash box which influences such factors as damage and safety of vehicles. As the simulation result can be agreed with experimental graph, all experimental data at this study are verified. These experimental results can be applied into real field effectively. It also proposes the effective design to improve impact performance by analyzing the property of crash box through its compressive test. 相似文献
87.
Large-Eddy Simulation (LES) was used to perform computations of air entrainment and mixing during diesel spray combustion.
The results of this simulation were compared with those of Reynolds Averaged Navier Stokes (RANS) simulations and an experiment.
The effect of LES on non-vaporizing and vaporizing sprays was evaluated. The validity of the grid size used for the LES analysis
was confirmed by determining the subgrid-scale (SGS) filter threshold on the turbulent energy spectrum plot, which separates
a resolved range from a modeled one. The results showed that more air was entrained into the jet with decreasing ambient gas
temperatures. The mass of the evaporated fuel increased with increasing ambient gas temperatures, as did the mixture fraction
variance, showing a greater spread in the profile at an ambient gas temperature of 920 K than at 820 K. Flame lift-off length
sensitivity was analyzed based on the location of the flame temperature iso-line. The results showed that for the flame temperature
iso-line of 2000oC, the computed lift-off length values in RANS matched the experimental values well, whereas in LES, the
computed lift-off length was slightly underpredicted. The apparent heat release rate (AHRR) computed by the LES approach showed
good agreement with the experiment, and it provided an accurate prediction of the ignition delay; however, the ignition delay
computed by the RANS was underpredicted. Finally, the relationships between the entrained air quantity and mixture fraction
distribution as well as soot formation in the jet were observed. As more air was entrained into the jet, the amount of air-fuel
premixing that occurred prior to the initial combustion zone increased, upstream of the lift-off length, and therefore, the
soot formation downstream of the flame decreased. 相似文献
88.
U. Hjorth 《Transportation Research Part B: Methodological》1999,33(8):345
From basic assumptions about independent and consistent driver behaviour, and with data from traffic counts, we derive statistical properties of regression or correlation estimates of route selection probabilities, turning probabilities and travelling times. Our modelling is conditional in a way that avoids most traffic generation problems and permits an asymptotic analysis of the precision under mild assumptions allowing non-stationarity. This allows us to put together non-stationary data from the corresponding time intervals during several days when we aim at high precision estimates. 相似文献
89.
With COP and dynamic characteristics in refrigeration cycle as criteria,a new metal hydride couple--LaNi4.61Mn0.26Al0. 13/La0.6Y0.4Ni4.8Mn0.2 was selected by establishing calculation procedure and metal hydride selection model. The experimental results show that the refigeration cycle of the selected couple is good in the performance. The recovered waste heat and refrigeration power from exhaust gas of several kinds of automobile are calculated by waste-heat formula ,coefficient RQ and COP. Refrigeration cycle of the new couple can satisfy the air-conditioning requirement of truck and car and is not enough in passenger car,according to the respective cooling load. 相似文献
90.
运用分形技术实现虚拟选线环境中的三维动态建模。所建模型能在铁路选线虚拟环境仿真系统中模拟地面、背景天空、树木等的三维图像。与传统的静态建模方法相比,这种建模方式不仅具有较高的真实性和多样性,而且对整个三维场景的运动速度影响非常小。运用分形技术进行动态建模的方法能够取得很好的视觉效果,所建模型不但能够满足铁路三维动态建模的要求,还可以应用到其它三维场景中。 相似文献