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551.
Carlton Basmajian 《Transportation》2010,37(1):59-84
Though driving to and from work has become a prevalent experience in the lives of individuals in every metropolitan region
in the US, much remains to be learned about the activity from the perspective of the drivers. To increase our understanding
of the motivation for certain travel behaviors, we must first know something about what those drivers experience. The existing
literature explains much, but the application of new methodologies could improve our ability to explain the willingness of
individuals to choose to drive through increasingly congested road networks. The results of this study of oral histories of
12 women commuters underscore the idea that commute should be seen as a set of subjective behaviors that contradict some existing
assumptions about why individuals commute. 相似文献
552.
Since Tian Jun proposed the difference expansion embedding technique, based on which, many reversible watermarking techniques
were proposed. However, these methods do not perform well when the payload is high. In this paper, we proposed an expandable
difference threshold controlled scheme for these three methods. Experiments show that our scheme improves the performance
of these three methods for heavy payload. 相似文献
553.
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
554.
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
555.
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
556.
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
557.
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
558.
A new generation conical spray system for conventional diesel engines or premixed combustion diesel engines is introduced. By means of oriented impingement method, flexible spray penetration in design is realized. High-speed photograph was used to investigate the spatial distribution characteristics of the new spray for cases of different impingement angles and needle valve opening pressures. The results show that, by applying spray impingement orientation, fuel jets spread along the cone surface as shape of sectors, so the dispersion of jets is increased obviously. Changing on impingement angle leads to variation of penetration, which is critical in homogeneous mixture preparation. Due to the flexibility of spray penetration in design, the spray impingement on liner is avoided in a great extent. The results also indicate that higher needle valve opening pressure results in longer penetration and larger spray angle after impingement. Combustion characteristics of the impinged conical spray were studied in the 1135 type diesel engine. The new impinged conical spray system work smoothly in full load range with better fuel economy and lower emissions of NOx and soot than the original test engine. 相似文献
559.
TAN Zhi-yong MU Yong ZHENG Hong-tao 《船舶与海洋工程学报》2005,4(3):42-46
A finite-rate method is used to simulate the three-dimensional combustion process in a plasma generator with CH4 as the fuel. The simulation was run with RNG k-ε model to simulate turbulence, with eddy-dissipation-concept (EDC) model to simulate the combustion and with discrete ordinates model to simulate radiation. The numerical results show that the flow field characteristics and the parameter distributions are under the condition of rich fuels, and these results provide valuable information when optimizing the plasma generator design and organizing its flow fields. 相似文献
560.
XIAO Bin YANG Tie-Jun LIU Zhi-Gang 《船舶与海洋工程学报》2005,4(4):34-42
In this paper, the reduced-order modeling (ROM) technology and its corresponding linear theory are expanded from the linear dynamic system to the nonlinear one, and H∞ control theory is employed in the frequency domain to design some nonlinear system' s pre-compensator in some special way. The adaptive model inverse control (AMIC)theory coping with nonlinear system is improved as well. Such is the model reference adaptive inverse control with pre-compensator (PCMRAIC). The aim of that algorithm is to construct a strategy of control as a whole. As a practical example of the application, the nunlerical simulation has been given on matlab software packages. The numerical result is given. The proposed strategy realizes the linearization control of nonlinear dynamic system. And it carries out a good performance to deal with the nonlinear system. 相似文献