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981.
Line heating process is a very complex phenomenon as a variety of factors affects the amount of residual deformations. Numerical
thermal and mechanical analysis of line heating for prediction of residual deformation is time consuming. In the present work
dimensional analysis has been presented to obtain a new relationship between input parameters and resulting residual deformations
during line heating process. The temperature distribution and residual deformations for 6 mm, 8 mm, 10 mm and 12 mm thick
steel plates were numerically estimated and compared with experimental and published results. Extensive data generated through
a validated FE model were used to find co-relationship between the input parameters and the resulting residual deformation
by multiple regression analysis. The results obtained from the deformation equations developed in this work compared well
with those of the FE analysis with a drop in the computation time in the order of 100 (computational time required for FE
analysis is around 7 200 second to 9 000 seconds and where the time required for getting the residual deformation by developed
equations is only 60 to 90 seconds). 相似文献
982.
浅底远程海底混响(英文) 总被引:1,自引:0,他引:1
杨士莪 《船舶与海洋工程学报》2010,9(1):22-26
The method of coupled mode is introduced for investigation of bi-static distant bottom reverberation of impulsive source in
shallow water, which will not contradict with principle of reciprocity in all cases. And the method of multi-pole for directional
source is also introduced. It shows that in case of layered medium, intensity of bi-static bottom reverberation will decease
according to the cubic power of receiving time t, and the transverse spatial correlation of bottom reverberation is a little greater than longitudinal correlation for equal
separation of receivers, and both vary in form with the receiving time. 相似文献
983.
In the Pearl River Delta (PRD), there is severe competition between container ports, particularly those in Hong Kong, Shenzhen, and Guangzhou, for collecting international maritime container cargo. In addition, the second phase of the Nansha terminal in Guangzhou’s port and the first phase of the Da Chang Bay container terminal in Shenzhen opened last year. Under these circumstances, there is an increasing need to quantitatively measure the impact these infrastructure investments have on regional cargo flows. The analysis should include the effects of container terminal construction, berth deepening, and access road construction. The authors have been developing a model for international cargo simulation (MICS) which can simulate the movement of cargo. The volume of origin-destination (OD) container cargo in the East Asian region was used as an input, in order to evaluate the effects of international freight transportation policies. This paper focuses on the PRD area and, by incorporating a more detailed network, evaluates the impact of several infrastructure investment projects on freight movement. 相似文献
984.
白令海潮汐能通量和底边界能耗散 总被引:1,自引:0,他引:1
The spatial distribution of the energy flux, bottom boundary layer (BBL) energy dissipation, surface elevation amplitude and
current magnitude of the major semidiurnal tidal constituents in the Bering Sea are examined in detail. These distributions
are obtained from the results of a three-dimensional numerical simulation model (POM). Compared with observation data from
seven stations, the root mean square errors of tidal height are 2.6 cm and 1.2 cm for M2 and N2 respectively, and those of phase-lag are 21.8° and 15.8° respectively. The majority of the tidal energy flux off the deep
basin is along the shelf edge, although some of this flux crosses the shelf edge, especially in the southeast of the shelf
break. The total M2 energy dissipation in the Bering Sea is 30.43 GW, which is about 10 times of that of N2 and S2. The semidiurnal tidal energy enters mainly to the Bering Sea by Samalga Pass, Amukta Pass and Seguam Pass, accounting more
than 60% of the total energy entering the Being Sea from the Pacific. 相似文献
985.
一种基于CFD的水动力系数计算新方法(英文) 总被引:3,自引:0,他引:3
Applications of computational fluid dynamic (CFD) to the maritime industry continue to grow with the increasing development
of computers. Numerical approaches have evolved to a level of accuracy which allows them to be applied for hydrodynamic computations
in industry areas. Hydrodynamic tests, especially planar-motion-mechanism (PMM) tests are simulated by CFD software -FLUENT,
and all of the corresponding hydrodynamic coefficients are obtained, which satisfy the need of establishing the simulation
system to evaluate maneuverability of vehicles during the autonomous underwater vehicle scheme design stage. The established
simulation system performed well in tests. 相似文献
986.
2009年4月,交通运输部批准了防城港、钦州港和北海三港统一归并,组成"广西北部湾港"。这标志着我国沿海又一个港口群的诞生。阐述了北部湾港口的建设与整合的目标和进展情况。分析了北部湾港口建设与整合对促进北部湾地区经济发展的重大意义。最后,提出了进一步健全北部湾港口管理体制、发展临港工业等5项对策。 相似文献
987.
988.
Mass transit projects are often a top contender of many cities to meet their increasing demand for travel. Despite the global
trend of privatization, mass transit services, as public goods, remain largely being provided and operated by the public sector.
Hong Kong is one of the few exceptions that all mass transit services are commercially operated. Both rail and bus services
in Hong Kong are reputable for their quality and profitability, often serving as benchmarks for new projects. In this study,
we investigate the factors contributing to this success. In particular, we ascertain the quality of transit service provision
by the private sector over the past two decades. Then, we conduct an in-depth analysis of the account books of leading railway
and bus operators in Hong Kong so as to shed light on their financial viability. Through this study, we hope to present crucial
factors for providing financially viable private transit services. 相似文献
989.
Yung-Hsiang Cheng 《Transportation》2010,37(6):875-896
Although people are often encouraged to use public transportation, the riding experience is not always comfortable. This study
uses service items to measure passenger anxieties by applying a conceptual model based on the railway passenger service chain
perspective. Passenger anxieties associated with train travel are measured using a modern psychometric method, the Rasch model.
This study surveys 412 train passengers. Analytical results indicate that the following service items cause passenger anxiety
during trains travel: crowding, delays, accessibility to a railway station, searching for the right train on a platform, and
transferring trains. Empirical results obtained using the Rasch approach can be used to derive an effective strategy to reduce
train passenger anxiety. This empirical study also demonstrates that anxiety differs based on passenger sex, age, riding frequency,
and trip type. This information will also prove useful for transportation planners and policy-makers when considering the
special travel needs of certain groups to create a user-friendly railway travel environment that promotes public use. 相似文献
990.
This paper seeks to explore the relationship between mode and destination choice in an integrated nested choice model. A fundamental
argument can be made that in certain circumstances, the ordering of choices should be reversed from the usual sequence of
destination choice preceding mode choice. This results in a travel demand model where travelers are more likely to change
destinations than to change transportation modes. For small and medium size urban areas, particularly in the United States,
with less well developed public transit systems that draw few choice riders, this assumption makes much more sense than the
traditional modeling assumptions. The models used in the new travel modeling system developed for Knoxville, Tennessee utilize
this reversed ordering, with generally good results, which required no external tinkering in the logsum parameters. 相似文献