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Urbanization and demands for mobility have spurred the development of mass rapid transit infrastructure in industrializing
Asia. Differences between the character of pre-existing urban structure in these localities and worldwide precedents suggest
a need for studies examining how new rapid transit systems function locally. This study of Bangkok’s elevated and underground
rail systems identifies relationships between the built environment and pedestrian behavior surrounding stations. Based on
details of 1,520 pedestrian egress trips from three elevated and three underground stations in 2006, multiple regression and
analysis of variance (ANOVA) revealed that types of pedestrian destinations, reflecting land uses, were related to length
of walking egress trips. Trips to shopping centers and office buildings were longer, while trips to eating places were shorter.
The most common type of pedestrian trip recorded was to another vehicle, and trips to automobile taxis and motorcycle taxis
figured prominently. Policy implications of the findings are considered. 相似文献
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Manivannan Kandasamy Daniele Peri Seng Keat Ooi Pablo Carrica Frederick Stern Emilio F. Campana Philip Osborne Jessica Cote Neil Macdonald Nic de Waal 《Journal of Marine Science and Technology》2011,16(2):143-156
The wakes of high-speed passenger-only ferries that operated through Rich Passage, on the Seattle-Bremerton ferry route, caused
beach erosion and damage to habitat. A task was initiated to design a low-wake high-speed vessel using multi-fidelity CFD
based design optimization by using low-fidelity potential flow solvers for initial global design optimization and by using
URANS solvers for high-fidelity tuning of the optimized design. This simulation based design process involved a close collaboration
between ship designers, and hydrodynamics and CFD specialists, whose collective expertise guided the evolution of the design
based on both hydrodynamic and structural aspects. The initial hull shape optimization using potential flow code was carried
out by blending three different initial concepts provided by the designers. Subsequently, URANS was used to evaluate the potential
flow optimized hull and to further optimize the hull configuration parameters, namely, the centre-of-gravity, demihull spacing,
foil location, foil angle and slenderness ratio at different displacement conditions. The URANS based configuration optimization
also took into account the far field wakes’ energy spectrum with an objective of reducing the energetic, low frequency far
field wakes which are associated with beach flattening on the mixed sand and gravel beaches. Calculation of the far field
wake using URANS would require an unfeasibly large domain size; therefore, a Havelock code with a source distribution matching
the URANS calculated near field wave elevation was used to propagate the wakes into the far field. The end result of the optimization
was a design with significantly reduced far field wake, which is currently being built for experimental testing. 相似文献
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Manivannan Kandasamy Seng Keat Ooi Pablo Carrica Frederick Stern Emilio F. Campana Daniele Peri Philip Osborne Jessica Cote Neil Macdonald Nic de Waal 《Journal of Marine Science and Technology》2011,16(2):157-167
This paper details the CFD validation studies carried out as a prerequisite for multi-fidelity CFD-based design optimization
of high-speed passenger-only ferries aimed at reducing far-field wake energy that causes beach erosion. A potential flow program
(WARP) and a URANS program (CFDSHIP) were validated using full-scale measurements of resistance, sinkage, trim, and far-field
wake train obtained over a wide range of speeds for two high-speed semi-planing foil-assisted catamarans: Spirit (LOA-22 m)
and 1060 (LOA-17 m). This study posed a unique combination of challenges for CFD modeling: the foil appended geometry required
complicated surface overset grids, the effect of the waterjet and wind resistance had to be modeled, and a method had to be
devised to extrapolate the calculated near-field elevation to get the far-field wake train using Havelock sources. A more
concentrated effort was applied to the URANS verification and validation which forms the focus of this paper. The results
show that URANS is able to accurately predict the resistance and motions for both vessels when coupled with models that account
for the propulsors and air resistance. The overall accuracy of URANS for the performance analysis of the foil-assisted, semi-planing
catamarans was adequate to warrant its use as a tool for subsequent design and optimization of a new vessel with significantly
reduced wakes. 相似文献
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James M. Vasslides Kim de Mutsert Villy Christensen Howard Townsend 《Coastal management》2017,45(1):44-55
Resource managers are often tasked with identifying and assessing the potential impacts of management actions on the biotic communities under their care. When the management activities directly influence a single species of interest, managers can turn to a variety of models to aid in their understanding of potential changes to that population. However, as ecosystem-based management becomes more widely accepted, managers will have to understand how proposed actions will impact entire biotic communities, through both direct and indirect mechanisms. Thus, there is a need for ecosystem models that account for both trophic and non-trophic interactions, and that can be relatively easily used to assess a variety of management scenarios. We reviewed the available literature regarding incorporation of eutrophication and other anthropogenic impacts into Ecopath with Ecosim (EwE), one of the more widely used trophic ecosystem modeling frameworks. We found that a number of mechanisms of varying complexity have been used to include these stressors in models, providing managers with a suite of options that can be used to complement their existing management options as they seek to understand the impacts of human interactions on the natural environment. 相似文献
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丹麦可能是世界上最容易找到好车的地方:当然我们说的是自行车。理由之一:在丹麦有近1/3的人是骑车上班,理由之二同时丹麦又是一个以设计闻名的国家。下面就来说说我们这位来自丹麦的主角:Michael Ubbesen Jakobsen—— 相似文献
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