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991.
Marshall Lindsey Joseph L. Schofer Pablo Durango-Cohen Kimberly A. Gray 《Transportation Research Part A: Policy and Practice》2010,44(9):697-709
The use of privately owned vehicles (POVs) contributes significantly to US energy consumption (EC) and greenhouse gas emissions (GHGe). Strategies for reducing POV use include shifting trips to other modes, particularly public transit. Choices to use transit are based on characteristics of travelers, their trips, and the quality of competing transportation services. Here we focus on the proximity of rail stations to trip origins/destinations as a factor affecting mode choice for work trips. Using household travel survey data from Chicago, we evaluate the profile of journey-to-work (JTW) trips, assessing mode share and potential for more travelers to use rail. For work trips having the origin/destination as close as 1 mile from rail transit stations, POVs were still the dominant travel mode, capturing as much as 61%, followed by rail use at 14%. This high degree of POV use coupled with the proportion of JTW trips within close proximity to rail stations indicated that at least some of these trips may be candidates for shifting from POV to rail. For example, shifting all work trips with both the origin/destination within 1 mile of commuter rail stations would potentially reduce the energy associated with all work-related POV driving trips by a maximum of 24%. Based on the analysis of trips having the origin and destination closest to train stations, a complete shift in mode from POV to train could exceed CO2 reduction goals targeted in the Chicago Climate Action Plan. This could occur with current settlement patterns and the use of existing infrastructure. However, changes in traveler behavior and possibly rail operation would be necessary, making policy to motivate this change essential. 相似文献
992.
按照《AAR机务标准手册》,对新型提速90 t凹底平车的牵引点布置在不同位置(布置在转向架上和布置在车体上)时由于车钩的偏移而作用在车辆上的横向力分别进行了计算,为确定总体方案提供了依据。 相似文献
993.
994.
Reliable research synthesis is of high significance for a transport policy which tries to base its decisions on available
empirical evidence. There is growing doubt whether the frequently used narrative approach provides a scientifically defensible
way of synthesising a body of quantitative research results. The present paper demonstrates meta-analysis as a more objective
and powerful alternative for this task. For this purpose evaluation data synthesised in two earlier narrative reviews on the
effectiveness of work travel plans [Cairns et al. Making travel plans work: research report (former), Department for Transport,
Local Government and the Regions (DTLR), London, 2002; Smarter choices—changing the way we travel. (Final report of the research project: The influence of soft factor interventions
on travel demand. Research report for the Department for Transport.) London. Retrieved 1 December 2005, from , 2004] are meta-analytically re-analysed and compared with the conclusions drawn from the narrative synthesis of these data. Our
meta-analyis provides only limited support for the conclusion that addressing parking is the hallmark of successful work travel
plans. Our meta-analysis indicates that site and organisational factors as well as characteristics of the monitoring process
are significant predictors of effective work travel plans, whereas Cairns et al. view little evidence for the impact of these
factors. 相似文献
995.
This paper addresses the issue of using before and after surveys to evaluate behavioural changes in response to transport
policies and investments, a procedure that, we argue is done far too rarely in this profession. Further, it demonstrates very
clearly that, in almost all conceivable cases, there are considerable economies to be obtained by using a panel (again, under-utilised
in our profession) to undertake evaluation, rather than successive independent cross-sectional surveys. The paper also addresses
the critical issue of sample size requirements for measuring changes of a relatively small magnitude in travel behaviour;
i.e., to state, with 95% confidence, that if there is a ∂ percent change in behaviour for the sample, there is a ∂ percent ± e
percent change in the behaviour of the population, where e is the sampling error. In this paper, we present a method for calculating such sample size requirements from first principles
and demonstrate the applicability both hypothetically and then empirically using data from the Puget Sound Transportation
Panel. The formulation enables designers of before and after surveys to investigate the trade-offs between the statistical
accuracy of their predictions and the sample size requirements systematically, without the need to specify ∂ a priori. This
latter point is crucial, we argue, because we have limited information on ∂, yet, as we explain here, it drives the sample
size requirements using alternative, well-cited approaches for calculating sample sizes to assess behavioural change. The
results have important ramifications both for those implementing transport policies intended to produce behavioural change,
especially when a cost-benefit evaluation of the policy is desired, and for those interpreting the results reported in previous
studies. 相似文献
996.
Martin F. Diez-Picazo 《WMU Journal of Maritime Affairs》2007,6(2):241-247
A cross-cutting Maritime Policy can ensure that climate change threats and challenges in regards to seas and oceans are dealt
with in a wide policy framework that takes into account the impacts that climate change may have on other sectors and vice
versa. 相似文献
997.
998.
Genetic algorithms (GAs) can powerfully search for parameters in a large multidimensional design space. Thus, the principle
can be applied to preliminary series propeller design problems with multiple considerations. In the present study, B-series
propeller design was conducted using a GA for both hydrodynamic efficiency and vibration consideration. The objective function
was set by users who could freely weight the relative importance of efficiency and vibration. GAs were successfully shown
to be able to obtain an optimal set of parameters leading to efficient performance and low vibration. 相似文献
999.
ZHU Guang-ping SUN Hui ZHANG Ming-hui 《船舶与海洋工程学报》2007,6(2):64-69
Array calibration is important in engineering practice. In this paper, fast calibration methods for a ULA's gain and phase errors both in far and near fields are proposed. In the far field, using a single sound source without exact orientation, this method horizontally rotates the array exactly once, performs eigen value decomposition for the covariance matrix of received data, then computes the gain and phase error according to the formulas. In the near field, using the same single sound source, it is necessary to rotate the array horizontally at most three times, build equations according to geometric relations, then solve them. Using the formula proposed in this paper, spherical waves are modified into plane waves. Then eigen values decomposition is performed. These two calibration methods were shown to be valid by simulation and are fast, accurate and easy to use. Finally, an analysis of factors influencing estimation precision is given. 相似文献
1000.
R. L. Cosgriff H. H. Yeh 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》1975,4(4):249-271
The dynamic shuttle system treated in this paper consists of main line trains traveling at a fixed speed. Passengers are shuttled to and from these fixed speed trains by means of shuttle cars. The shuttle cars can provide local service and thus alleviating the need for stations along the route of the main line trains. The main line trains have a peak volume, depending upon operating speed which is an order of magnitude greater than existing modes. They provide high speed service to travelers in the belt traversed by the trains. 相似文献