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181.
以潜艇操纵面的几何尺度和纵向位置为设计变量,估算归一化后的无因次水动力系数,建立潜艇操纵性指标预报数学模型.基于iSIGHT优化平台,采取NCGA遗传算法开展潜艇操纵性指标的多目标优化设计,给出改进的优选方案,并进行灵敏度分析,评估操纵面参数对操纵性指标的影响. 相似文献
182.
Runyu Wang 《WMU Journal of Maritime Affairs》2011,10(2):143-165
Since the 1980s, the precautionary principle has been drawing more and more international attention. This became particularly
clear during the series of Conferences on the Protection of the North Sea, which addressed marine environmental protection,
and initiated the application of the principle into maritime affairs. Although a unified concept of the precautionary principle
is lacking, some typical formulations have been concluded in regional treaties and international documents, and components
of the principle can be summarised (Part I and Part II). The precautionary principle has been adopted by international documents
involving different fields of law of the sea, and been addressed by international courts and tribunals (Part III). While the
precautionary principle is still not part of customary international law (Part IV), its increasing level of worldwide acceptance
suggests that it will become a customary international law in the future. 相似文献
183.
The present investigation deals with process analysis of oxy-acetylene flame assisted double pass line heating for varying plate thickness. oxy-acetylene flame as the heat source for multi pass line heating to achieve 3-D bending of plates with varying thicknesses was studied. The oxy-acetylene flame was modeled as the moving heat source in the FEM analysis. The transient thermal histories were predicted taking into account the temperature dependent thermo-mechanical properties. A comparative study between single pass and double pass line heating residual deformation was also carried out. The temperature distribution and residual deformations predicted by the numerical model developed in the present work compared fairly well with those of the experimental ones. 相似文献
184.
This paper documents the efforts to operationalize the conceptual framework of MIcrosimulation Learning-based Approach to
TRansit Assignment (MILATRAS) and its component models of departure time and path choices. It presents a large-scale real-world
application, namely the multi-modal transit network of Toronto which is operated by the Toronto Transit Commission (TTC).
This large-scale network is represented by over 500 branches with more than 10,000 stops. About 332,000 passenger-agents are
modelled to represent the demand for the TTC in the AM peak period. A learning-based departure time and path choice model
was adopted using the concept of mental models for the modelling of the transit assignment problem. The choice model parameters
were calibrated such that the entropy of the simulated route loads was optimized with reference to the observed route loads,
and validated with individual choices. A Parallel Genetic Algorithm engine was used for the parameter calibration process.
The modelled route loads, based on the calibrated parameters, greatly approximate the distribution underlying the observed
loads. 75% of the exact sequence of transfer point choices were correctly predicted by the off-stop/on-stop choice mechanism.
The model predictability of the exact sequence of route transfers was about 60%. In this application, transit passengers were
assumed to plan their transit trip based on their experience with the transportation network; with no prior (or perfect) knowledge
of service performance. 相似文献
185.
This paper establishes a link between an activity-based model for the Greater Toronto Area (GTA), dynamic traffic assignment,
emission modelling, and air quality simulation. This provides agent-based output that allows vehicle emissions to be tracked
back to individuals and households who are producing them. In addition, roadway emissions are dispersed and the resulting
ambient air concentrations are linked with individual time-activity patterns in order to assess population exposure to air
pollution. This framework is applied to evaluate the effects of a range of policy interventions and 2031 scenarios on the
generation of vehicle emissions and greenhouse gases in the GTA. Results show that the predicted increase of approximately
2.6 million people and 1.3 million jobs in the region by 2031 compared to 2001 levels poses a major challenge in achieving
meaningful reductions in GHGs and air pollution. 相似文献
186.
In an attempt to reduce CO2 emissions from motorized transport, the Taiwanese government introduced an idling stop policy for vehicles in early 2007.
This paper seeks to quantify the environmental benefits of the policy based on a stated preference analysis. Motorcyclists
were surveyed at urban intersections in Taiwan, to identify the amount of time they would be willing to turn off their engines
while waiting at traffic lights (the WTO). A contingent valuation framework based on stated preference questions was designed
to determine the WTO. Results obtained from the Spike model showed that the average motorcyclist’s WTO is 82 s. In another
analysis, in which other variables were taken into consideration, such as the possibility that the policy will be enacted
as legislation, the expected WTO increased to 101 s. In both cases, an idling stop policy would have positive environmental
effects, reducing gasoline usage by 1021 L per hour and reducing CO2 emissions by 0.56 metric tons per hour at the intersection studied during peak periods. 相似文献
187.
This paper examines the location choice associated with discretionary activities (in-home vs. out-of-home). These substitution
patterns are important in terms of travel demand as in-home activities do not necessitate travel while out-of-home activities
incur travel. Mixed logit models are estimated using an activity dataset (2003 CHASE data) to analyze the factors associated
with this choice at the individual activity-level. Results suggest that the attributes of an activity significantly contribute
to understanding the likelihood of engaging in out-of-home activities. Activity type interaction terms reveal the varying
influence that socio-demographics, activity attributes and travel have over four different activity types modeled. The results
reveal that the location choice (in-home vs. out-of-home) is sensitive to travel characteristics. As the travel time and cost
increases, an individual is less likely to engage in an activity out-of-home. Compared to passive and social activities, the
location of active activities is more sensitive to changes in travel attributes. 相似文献
188.
Reliability in cost estimates in publicly funded projects is more important today than ever with increased governmental funding
to infrastructure projects and associated accountability requirements, but surface transportation projects, large and small,
in the United States have a legacy of cost overruns. The problems with these overruns start with the cost estimation process
before projects begin. Studies have shown that early cost estimations reflect best-case scenarios rather than realistic expectations,
and have attributed technical, economic, psychological, and political reasons for underestimation. The primary objectives
of this research were to determine how costs have been presented and updated in environmental impact statements, to identify
endemic technical problems with cost estimation during the environmental review of surface transportation projects, and to
develop recommendations for improving cost estimation and disclosure. Cost estimation methods were analyzed from the documents
of 100 projects, including draft environmental impact statements, final environmental impact statements, and records of decision.
The study concluded that the lack of guidance on how to include cost estimation in environmental review revealed itself in
the level of detail and attention given to estimating costs. Agencies omitted or included various aspects of cost estimation
randomly. Professional organizations should fill the gap of the need for specific guidance to cost estimation for environmental
review so it can evolve as a state of the practice. 相似文献
189.
This paper seeks to improve our understanding of passengers’ behavioral intention by proposing an integrated framework from
the attitudinal perspective. According to the literature in marketing research, we establish a causal relationship model that
considers “service quality-satisfaction-behavioral intentions” paradigm, perceived value theory, and switching barrier theory.
Exploring passengers’ behavioral intention from satisfaction and perceived value help to understand how passengers are attracted
by the company, while switching barriers assist in realizing how passengers are “locked” into a relationship with the current
company. Furthermore, in order to capture the nature of service quality, we adopt a hierarchical factor structure which serves
service quality as the higher-order factor. In this study, coach industry is selected as our research subject. The empirical
results, as hypothesized, show that all causal relationships are statistically significant, and perceived value us the most
important predictor of satisfaction and passengers’ behavioral intention. In conclusion, the managerial implications and suggestions
for future research are discussed. 相似文献
190.
Evangelia N. KaselimiAuthor Vitae Theo E. NotteboomAuthor Vitae Athanasios A. PallisAuthor Vitae Sheila FarrellAuthor Vitae 《Research in Transportation Economics》2011,32(1):71-80
The decision on the scale of a port terminal affects the terminal’s managerial, operational and competitive position in all the phases of its life. It also affects competition structures in the port in which the terminal is operating, and has a potential impact on other terminals. Port authorities and terminal operators need to know the scale of the terminal when engaging in concession agreements. In economic theory the scale of a plant/firm is typically defined in relation to the Minimum Efficient Scale (MES), the long-run output where the internal economies of scale are fully exploited. However, there are a number of theoretical and empirical indications that in ports the scale of a terminal is commonly guided by a combination of the MES and other determining factors. The “preferred” scale is the result of a complex interaction between the MES, the port governance framework and objectives, the market size and structure, technological change and operational considerations, physical and geographical limitations, and the business patterns of shipping lines. This study analyses the factors resulting in a preferred container terminal scale that in most of the times is different from the MES. The analysis of the technical, market-related and governance-related factors is supported by theoretical and empirical insights that illustrate the presence of a range of actual ”preferred” scales of terminal concessions that usually are different, below or above, MES. 相似文献